CSI demystified! - CSI

之前收集大家的問題，去問現實生活中的CSI，
已經得到回覆了
而且...非常的落落長.......

我先把回答貼過來，
請善心人士有空幫忙翻一下囉。
（會不會直接按end啊 XD）

看來這位大哥叫做Larry, 在德州的 crime lab 工作
專精的是有關毒品方面的檢驗
所以有些問題他也只能就他所知回答，
畢竟術業有專攻，
他在回答中也有提到，
現實生活中的 CSI 其實是比電視上分工還要細，
而不是像電視上那樣每個人都是全才。
（其實我覺得本店第一季還有根據個人的專長稍做著墨，後來變得好像
每個人都什麼都會）

當CSI有什麼條件，我覺得可以看一下，
看完以後會覺得這真是個崇高的工作 ^^
不過據這位大哥說沒有身高限制，也沒有視力限制，
他是作毒品分析的，所以有化學方面的背景是最好的，
不過看你是要作哪方面的分析，所需要的背景也各有不同。
他說真正跑DNA分析其實不會太久，
真的久的是準備分析的樣本，而大多數實驗室之所以會花很多時間，
是因為案子積太多了！




>What does it take to be a CSI? Is there a requirement on height?

A: To answer the 2nd question first, there's no height requirement for
forensic scientists in real life. (Nor, luckily for me, is there a
photogenicity requirement. LOL) Back to the first question, I
really think the most important requirement to be a good CSI is to have an
inquiring mind, and by that I mean be interested in a lot of different
subjects. You also have to be meticulous (since recording the results of the
analyses, whether it's weights of drugs, or allele matches in DNA, or
whatever, has to be done as accurately as possible), patient (because despite
the glamorous image portrayed by the TV show, a lot of the work is very
repetitive), detail-oriented (able to assess and keep in mind a wide range of
tiny facts) yet also able to see the "big picture" (don't lose sight of the
overall goal, just because you're concentrating on small details at any
particular moment), have good laboratory technique (since sloppiness can lead
to incorrect results or incorrect assessments of the results), be objective
and truthful (since you will testify as a forensic expert in courts of law
about the results you obtain - and you must favor neither the prosecutor nor
the defendant, but allow your scientific observations to speak for
themselves), able to explain complex analyses in lay terms (because by and
large, the juries who will hear your testimony are *not* scientists), not be
overly shy (you will be explaining your work and results before a jury of
about a dozen people, as well as the judge, court reporter, and prosecuting
and defending attorneys, and perhaps court visitors as well - and since we
have an "adversarial" legal system in the U.S., the defense attorneys can try
to discredit your work or your results - and may even resort to somewhat
personal attacks), and fairly quick-thinking (to respond to the attorneys'
questions; the defense's questions in particular are unlikely to be
"scripted"). It sometimes helps, too, to be a little thick-skinned. Not only
are crime scenes sometimes (often?) messy to filthy to nasty, but also you'll
have some limited contact with the less-than-stellar members of our society -
or at least you may be working with their body fluids. So in addition to all
the technical stuff, you also have to keep in the back of your mind an
awareness that the material you're working with may be infectious, or toxic,
or explosive. You have to be careful, and it boils down to remaining
intellectually alert even if the task at hand appears at first glance to be
the same test you've already run 10,000 times in your career. If your goal is
to analyze "controlled substances" (drugs), it would be a good idea not to
take them for a test drive in your personal life. The U.S. DEA (Drug
Enforcement Administration) *says* that "limited, youthful experimentation
with marijuana" will not necessarily bar you from being hired by them - but
believe me, the competition for the positions is so intense that it will in
fact be the kiss of death - and experimentation with any other drug also will
definitely knock you out of the race. Every forensic organization I know of
automatically excludes applicants that have any felony conviction - so, also
avoid DWI (driving while intoxicated), as well as any more serious illegal
activities (drug sales/manufacture, murder, rape, forgery, burglary, bank
robbery, etc - they're all no-no's). In other words, live your life so as to
be
able to withstand a complete and detailed background investigation.

>What kind of background do you have to have (e.g. biology, chemistry,
physics, etc.)

A: For drug analysis [which is my specialty] a strong chemistry background
(B.S.) is the best. There are universities that offer a "forensic science"
degree, but in my opinion these programs are not sufficiently rigorous in
hard science and math. If you want to become a DNA analyst, then you should
have a background in biology, including courses in genetics and molecular
biology; a course in statistics also might be good to have, since your
testimony will include explaining the probability of DNA matches to a jury of
laypeople. (And just like in graduate seminars, you should know roughly 5-10
times as much as you say in your "prepared" speech.) For forensic computer
analysts (for example, money laundering schemes, conspiracies, drug dealers,
porn rings including child porn, hackers/crackers, etc) obviously you should
have an in-depth
background in computers, including knowledge of a number of different
operating systems, applications, some programming languages, and all sorts of
peripherals; detailed knowledge of storage components' operation (hard
drives, CDs, DVDs, floppies, ZIP drives, etc), and at
least a working knowledge of networking software and equipment. There is
forensic software that will help you, and it's been vastly improved since the
early days, but you'll still need to be very
detail-oriented and meticulous. For trace analysis (hair, fibers, paint,
cloth, paper) chemistry is still a good background, since the laboratory
courses teach you to be meticulous and expose you to the scientific method -
which really is just a framework to guide you in your analyses. For the
firearms/toolmarks subdiscipline, an interest in guns is useful, but you also
have to be able to visualize how things compare (do striations on a
particular "evidence" bullet match the ones on another bullet fired from the
suspect weapon?) or how they fit together (to see, for example, if the marks
on a window frame could have been made by the crowbar submitted as evidence in
the case). Some other disciplines such as fingerprint analysis and questioned
document analysis don't so much require a hard science background as the
ability to discern small details and small
differences. Fingerprint analysis has been automated through computer
matching, but the final comparison is still done by human analysts. Other
subdisciplines such as explosives investigations are pretty much "OJT"
(on-the-job training) fields, but again a good background
in science will give you the sort of disciplined analytical approach that
will prove useful.

>How long does it take to get a DNA result?

A: The actual analysis doesn't take terribly long - say overnight. Preparing
the samples for analysis takes longer - a day to a week or more, depending
how much evidence is submitted. (The huge number of samples from the 9/11
incident and the Oklahoma City bombing took
many months to process.) The reason it takes most labs a long time to return
results is that nearly all of them have tremendous backlogs of evidence
waiting to be analyzed, and unfortunately the trend is that the backlogs are
increasing rather than decreasing. In our lab, it may take only 30 minutes to
actually analyze a particular exhibit - but it takes about 6 months to work
through all the other cases that were submitted before that one. Our
turnaround time has increased
from about 2 months to about 6 months over the past 2 years, mostly because
we've had a huge increase in the number of cases that are submitted to us for
analysis during that time.

>Is it still possible to test for DNA on a cotton swab if it had been sprayed
with luminal?

A: This isn't really my field, so I'm not sure. It depends on whether the
solvent for the luminol "denatures" or decomposes the DNA. I seem to recall
that when luminol is used on a surface (a painted wall, say) that had blood
smear on it, DNA can still be recovered from the area where the luminol
indicates blood was present. But I may be thinking of visually-apparent
(*without* luminol) blood spatters. DNA would quite likely be recoverable
from those, if they're not too old.

>Is it really possible to enhance the images on surveillance tapes the way
they do on the show?

A: This is possible, yes. Good photo "retouching" software does the same sort
of thing (increase/decrease contrast, increase sharpness) and more
specialized software can even convert small differences in color in the
original image to contrasting colors to provide the
effect of even more enhancement.

>How much can you enhance the images?

A: Again, it's not my field, but I suspect it's less than what they show on
CSI. I could be wrong, though - recall that many of the photo enhancement
techniques (software) were originally developed for military applications and
clandestine intelligence ("spy") operations, and those are quite
sophisticated. How much of that technology has filtered down to the law
enforcement/forensics community, I'm not sure. It's probably a safe bet that
the military/intelligence software is better than what's available to
forensic analysts, which is better than what's (usually) available to
joe-on-the-street.

>What do you think about the show (the CSI franchise)?

A: If you keep it in perspective, that at its heart it's *entertainment* -
then in that sense I enjoy it. In terms of the science, it seems fairly
true-to-life most of the time. In terms of the amount of time it takes to
analyze a case, it takes a lot longer and is a lot less glamorous than the
way it's portrayed by the show. Most forensic analysts nowadays are more
specialized than is shown,
but as I said earlier, wide-ranging interest in and knowledge of a variety of
subjects can be a very useful talent. The Journal of Forensic Science is
probably available to you at the university library, and will show you the
wide variety of subjects that the field covers. Nowadays nearly all forensics
people are specialists in one or at most only a few sub-disciplines of the
field.

>Do more people get into this career because of the show?

A: I think interest in the career field has definitely been heightened by the
show. The downside is that the work's not nearly as glamorous as the show
makes it seem. Sure, especially early on in
your career, there's a bit of the "snob factor" that you were selected to
work in a career that has its interesting moments. I hadn't had any exposure
to street drugs before I began working for the crime lab, so that was
interesting for a few months - but like any job, there is so much repetition
of seeing "the same old thing" that you have to work to maintain your
interest. There are various ways to do that; one is to remain focused on the
job at hand and consider each case as a fresh challenge to be solved (and
keep in mind that *somebody* - at least the defendant if not his/her family)
is vitally interested in your results and in being assured that you did your
best to be objective and truthful); another is to expand your knowledge to
other forensic sub-disciplines, by talking with your colleagues, attending
seminars and conferences, getting additional training, and reading. Think of
the rock stars from the 80's or even the 60's - how do they keep their
renditions of the standards their group has sung 1000s and 1000s of times,
fresh for tonight's concert? It's a combination of training, self-discipline,
and living in the moment. It's the thrill of meeting the challenge and
solving the problem. I think that's the same for any job that you plan to
stick with long-term - you sort of have to devise ways to keep yourself
interested and challenged and fresh.

>Is it more difficult to solve the cases because of the show?

A: I don't think it's more difficult to solve most of the cases. I do think
the public has an expectation that *any* case can be solved by the crime lab,
and that's not true. Nor are we infallible. Despite our very best efforts and
very best intentions, despite all of the quality checks we build in to the
system, in a very small number of cases, we make errors. (That fact is always
in the back of my mind, and it just makes me all the more determined to do my
very best to be
accurate and truthful in my interpretations of my analytical results.)
There's also a mistaken impression that all or nearly all cases can be solved
_quickly_ by the lab, and that's not necessarily true.

>What is the percentage of cases solved using forensic techniques?

A: I don't have a number, but usually forensics is an *adjunct* to plain old
detective work. For example, in my case, I don't go out and bust drug
dealers; all I do is analyze their wares. If the case goes to court, all of
the observations and actions by the patrol officers and the narcotics
detectives (what they did and why they did it) has to be related to the
jury, and comes under scrutiny by the defense lawyers. There has to be
"probable cause" for the arrest. Custody of the evidence has to be controlled
and documented, to insure that it wasn't contaminated or tampered with prior
to its arrival in the lab. My analysis of the evidence is just the end of the
whole process -
and if the analysis shows that there were no drugs present after all (the guy
was selling sugar instead of meth, maybe), then the whole case collapses and
the charges are dismissed. If drugs were actually present, the defendant may
decide to plead guilty and not go to trial. Even if there is a trial, if the
defense counsel is able to show there was a break in the chain of custody of
the evidence (such that the evidence I analyzed might *possibly* not be the
same evidence that was seized from the defendant at his arrest) or that there
was not legal probable cause to justify the arrest, then the case ends. If
all the other requirements are met, then the prosecutor
still has to show that I'm qualified as a drug analysis expert (this is done
based on my educational background and experience) before I can testify about
how I analyzed the evidence and what the results of my analyses were. My
analysis is like the final piece in the puzzle. In cases of rape or murder,
forensic analysis can become the linchpin to the entire case. There have been
a few cases where a person was convicted based on old (pre-DNA) serological
techniques, and
subsequent re-analysis using modern DNA techniques actually *exonerates* the
person. There are also some cases that have been solved via CODIS (Combined
DNA Indexing System - a national DNA database) matches, where traditional
investigative/detective techniques have run into a dead end. Usually though,
forensics provides the "nail in the coffin" that provides the conclusions
formed during the preceding detective work with some scientific certainty.

>Do all cases require CSIs?

A: No, definitely not. Nowadays most drug cases as well as sexual assault
cases will make use of forensic analysis. Murder cases can often make use of
forensics, for trace analysis and/or firearms analysis, and possibly for DNA
analysis. Driving while intoxicated cases depend on analysis for alcohol or
drugs. Burglary cases *may* use forensics (for example to match the tools
used to break in, with the marks they left behind at the crime scene, or DNA
traces). But many other cases, such as domestic violence, simple assault,
fraud, robbery, speeding tickets, streaking (just kidding - are you still
paying attention?) - don't usually involve CSI types.

>Do you sometimes turn to psychics to solve the case?

Well, sometimes I think that's how my supervisor does his analyses.... I'm
kidding again. I've never been involved in any case where psychics were
brought in. I like to try to keep an open mind, but I suspect that most
psychics are charlatans. Still, there are phenomena in the world that haven't
been fully explained.

>Do CSIs carry guns?

A: Not in Texas state crime labs. I wouldn't trust some of the people with
them, so I'm just as glad we don't. In some other states, they do (see below).

>Are CSIs civilians? Field investigators too? Or do they carry badges? Is the
situation the same across states?

A: In some states, the crime lab analysts are sworn law enforcement officers
- in a word, badge-carrying, gun-totin' police officers. That's true in
Oklahoma, for example, and I think also in Colorado. In Texas and California,
most of the crime lab analysts are *not* sworn police officers - they're
civilians, so no badges other than our ID cards. Regarding field
investigations, we do occasionally do these. The ones I have participated in
involved so-called clandestine laboratories - illegal drug manufacturing
labs. Here in Texas, it's illegal to sell/buy most chemical glassware without
a state permit, so the labs usually made do with equipment improvised from
pyrex mixing bowls, measuring cups, hot plates, etc. In California I don't
think they have that restriction, right? So the CSI types there could see
more sophisticated setups that might look more like a traditional
chemistry lab. Still, by and large the crooks are *not* chemists - the
recipes and techniques are passed around via the prison and criminal
underground, so generally they don't really have any grasp of the science.
(That's not always true - there was a case of a self-educated chemist in the
Midwest that was making fentanyl in an old abandoned ICBM missile silo. He
had to have quite a sophisticated setup, since the drug is some 10x stronger
than heroin - fatal in sub-milligram amounts, and this guy was making
kilograms of the stuff!) Their lack of knowledge is the reason a fair number
of clandestine chemists end up dead; the ones that live often come down with
strange cancers later in their lives. One common method for making
methamphetamine uses red phosphorus - but a small change in the reaction
conditions can also produce the deadly gas phosphine. There are books
available that supposedly show you how to synthesize nerve gases - but *I*
sure wouldn't want to try it in a clandestine lab setting - nor even in a
well-equipped lab with fully functional fume hoods!

>Do crime labs process their own evidence, or do they send it out to outside
labs for processing?

A: Usually, crime labs analyze their own evidence. There are some sorts of
analyses that require specialized equipment that a particular lab may not
have, so those would be sent to an outside lab. In Texas, for example,
although there are 13 state crime labs total (the headquarters lab in Austin
+ 12 "field" labs scattered around the state), only the HQ lab has an XRD
[X-ray diffraction]
instrument. So if XRD analysis were needed, that evidence would be sent to
the HQ lab. None of the state crime labs perform an analysis for marijuana in
blood, so those cases (which are relatively few) are sent to private
analytical labs. It's most common for crime labs to be able to analyze seized
drugs, blood alcohol (from driving-while-intoxicated cases), trace evidence,
fingerprints, and DNA and serology [though serology is becoming less common].
Many crime labs also do firearms/toolmarks testing and questioned documents
analyses (hot checks, fraudulent securities, etc). Computer forensics is also
becoming more common. In our lab system, computer forensics is part of the
questioned documents lab (at HQ). The headquarters lab has sections that deal
with all of the forensic subdisciplines, whereas individual field labs may
only have a few of the specialties. Where I work, we only do drug analyses
and blood alcohols. In El Paso, they have those plus DNA and firearms/
toolmarks sections. In Waco, they have drugs, blood alcohol, and DNA. In
Tyler, there's drugs, blood alcohol, and firearms, but no DNA. In Amarillo,
all they do is drug analyses. So it varies from lab to lab and state to state.

Thanks for your questions! It's not often I get to talk at length about what
I do to anyone outside the law enforcement/criminal justice community, so
it's been a lot of fun to have the opportunity.
I've been in the forensics field for 8.5 years now, and I was an analytical
(quality control) chemist in industry for about 8 years before that. As far
as schooling, oy vay I was an undergrad/grad chem. student for *far* too many
years! LOL - Obviously I like chemistry - a lot! That has served me well in
this job, because I go off on little tangents when something unusual comes
across my bench to analyze. That's what helps keep the job interesting!

-- Larry


--
Sara: Would you like to have dinner with me?
Grissom: (pause) No .
Sara: Why not? Let's..let's have dinner..let's see what happens.
Grissom: Sara..(sigh)..I don't know what to do about THIS.
(gesturing towards them both)
Sara:I do. You know by the time you figure it out,you really could be too late.

--