HOW DNA TESTING WORKS (Анализ ДНК как проверяющие работы)
HOW “DNA” TESTING WORKS
The tools for solving rapes and murders have improved rapidly. Five years
ago DNA tests couldn’t link suspects to hair or semen found on a victim.
Today a crime lab can identify unique DNA patterns in a tiny sample of just
100 to 200 cells. The steps scientists take to implicate or exonerate
suspects:
1) Collect biological materials from the crime scene and the suspect
under investigation, such as blood, hair, semen or saliva. Every
cell is a unique library of DNA sequences. The goal is to find out
if the forensic and suspect’s samples match.
2) Isolate pure DNA by mixing the sample with chemicals that break
down other cellular material. DNA molecules consists of paired
filaments that interlock like zippers, and each filament is made up
of chemicals “bases” (A, C, T and G) aligned in unique sequences.
3) Amplify the DNA by separating paired filaments and mixing them with
short fragments known as primers. When a primer locks onto a
particular site on a sample DNA molecule, it triggers production of
a longer fragment that matches a piece of the sample.
4) Segregate the resulting DNA strands. A sample mixed with 13
primers multiplies into millions of distinctive molecules. Exposed
to an electrical current, the molecules a sorted into color-coded
bands on a gel.
5) Compare the crimescene samples with the suspect’s. Scientists say
it’s virtually impossible for unrelated people to match up
perfectly on 13 different levels. If samples do, odds that they’re
from one person are overwhelming.
Helped prove the innocence of Anthony Porter, who at one point had
been just two days shy of lethal injection for a pair of 1982 murders. Once
again, the issue in Illinois wasn't the morality of death sentences, but
the dangerously sloppy way in which they were handed out. Once again a
confession from another man helped erase doubt that the man convicted of
the crime, who has an IQ of 51, had committed it.
By last fall the list of men freed from death row in Illinois had
grown to 11. That's when the Chicago Tribune published a lavishly
researched series explaining why so many capital cases were suspect. The
Tribune’s digging found that almost half of the 285 death-penalty
convictions in Illinois involved one of four shaky components: defense
attorneys who were later suspended or
disbarred, jailhouse snitches eager to shorten their own sentences,
questionable "hair analysis" evidence or black defendants convicted by all-
white juries. What's more, in the weeks after those stories appeared, two
more men were freed from death row. That pushed the total to 13 - one more
than the number of inmates Illinois had executed since reinstating the
death penalty in 1977.
The Porter case and the Tribune series were enough for Governor Ryan.
On Jan. 31, he declared a moratorium on Illinois executions, and appointed
a commission to see whether the legal process for handling capital cases in
Illinois can be fixed. Unless he gets a guarantee that the system can be
made perfect, Ryan told NEWSWEEK last week, "there probably won't be any
more deaths," at least while he's governor. "I believe there are cases
where the death penalty is appropriate," Ryan said. "But we've got to make
sure we have the right person. Every governor who holds this power has same
fear I do.”
But few are acting on it. In the wake of the Illinois decision, only
Nebraska, Maryland, Oregon and Nrw Hampshire are reviewing their systems.
The governors of the other states that allow the death penalty apparently
think it works adequately. If they want to revisit the issue, they might
consider the following factors:
Race: The role of race and the death penalty is often misunderstood.
On one level there's the charge of institutional racism: 98 percent of
prosecutors are white, and, according to the NAAGP, Legal Defense Fund they
are much more likely to ask for the death penalty for a black-on-white
crime than when blacks are the victims. Blacks convicted of major violent
offenses are more likely than white convicts to end up on death row. But
once they get there, blacks are less likely than white death-row inmates to
he executed because authorities are on the defensive about seeming to
target African-Americans. The result is both discrimination and reverse
discrimination - with deadly consequences.
The risk of errors: The more people on death row, the greater chance
of mistakes. There are common elements to cases where terrible errors have
been made: when police and prosecutors are pressured by the community to
"solve" a notorious murder; when there's no DNA evidence or reliable
eyewitnesses; wnen the crime is especially heinous and draws large amounts
of pretrial publicity; when defense attorneys have limited resources, if
authorities were particularly vigilant when these issues were at play, they
might identify problematic cases earlier.
Deterrence: Often the first argument of death-penalty supporters. But
studies of the subject are all over the lot, with no evidence ever
established of a deterrent effect. When parole was more common, die
argument earned more logic. But nowadays first-degree murderers can look
forward to life without parole if caught, which should in theory deter diem
as much as die deadi penalty. It's hard to imagine a criminals thinking:
"Well, since Г might get the death penalty for this crime, 1 won't do it.
But if it was only life in prison, I'd go ahead."
inadequate counsel: Beyond the incompetent lawyers who populate any
court-appointed system, Congress and the Clinton administration have put
the nation's 3,600 death-row inmates in an agonizing Catch-22. According to
the American Bar Association Death Penalty Representation Project, in a
state like California, about one third of death-row inmates must wait for
years to be assigned lawyers to handle their state direct appeals. And at
the postconviction level in some suites, inmates don't have access to
lawyers at all. The catch isdiatdie 1996 And -Terrorism and Effective
Deatii Penalty Act has a statute of limitations requiring diat inmates file
federal habeas corpus petitions (requests for federal court review) within
one year after die end of their direct state appeal. In other words,
because they have no lawyer after their direct appeals, inmates often
helplessly watch die clock run out on their chance for federal review. This
cuts down on frivolous appeals—but also on ones that could reveal gross
injustice.
Fact-finding: Most states aren't as lucky as Illinois. They don't have
reporters and investigators digging into die details of old cases. As die
deadi penalty becomes routine and less newsworthy, the odds against real
investigation grow even worse. Аж1 even when fresh evidence does surface,
most states place high barriers against its use after a trial. This has
been standard in the legal system for generations, but it makes little
sense when an inmate's life is at stake.
Standards of guilt: In most jurisdictions, die judge instructs the
jury to look for "guilt beyond a reasonable doubt." But is that the right
standard for capital cases? Maybe a second staridard like "residual doubt"
would help, whereby if any juror harbors any doubt whatsoever, the
conviction would stand but the death penalty would be ruled out. The same
double threshold . might apply to cases involving single eyewitnesses and
key testimony by jailhouse snitches with in-----
Cost: IJnless executions are dramatically speeded up (unlikely after
so many mistakes), the death penalty will remain far more expensive than
life widiout parole. The difference is in the upfront prosecution costs,
which are at least four times greater dian in cases where death is not
sought. California spends an extra $90 million on its capital cases beyond
die normal costs of the system. Even subtracting pro bono defense, the
system is no bargain for taxpayers.
Whether you're for or against die deadi penalty, it's hard to argue
diat it doesn't need a fresh look. From America's earliest days, when
Benjamin Franklin helped develop the notion of degrees of culpability for
murder, diis country has been willing to reassess its assumptions about
justice. If we're going to keep die deadi penalty, die public seems to be
saying, let's be damn sure we're doing it right. DNA testing will help. So
will odier fixes. But if, over time, we can't do it right, then we must ask
ourselves if it's worth doing at all.
HOW “DNA” TESTING WORKS
The opening DNA is a new era in development of a science and society, it
opens new opportunities, which were inaccessible earlier, and is capable to
help not only scientist and patient, but also policeman with disclosing a
crime. Now already it is impossible to present as five years ago managed
without any help of DNA.
Now the laboratory can identify samples found on a place of a crime,
with samples suspected, and then to make a conclusion about participation
suspected with accuracy on 99 %.
The analysis DNA consists of five stages:
1)Collect
2)Isolate
3)Amplify
4)Segregate
5)Compare , during which is found out, whether the found samples on a
place of a crime suspected belong. It is very heavy process, which requires
large material inputs, and human forces. But result can’t be valuable.
As the opening DNA has helped sharply to lower a judicial mistake,
which were not a rarity, at removal court of a death penalty. Very much
often executed the innocent people, which than could not prove the
innocence. Now, at use DNA, the probability of a mistake has decreased in
Страницы: 1, 2
