【分析解答题】

British police forces are reviewing more than 450 unsolved crimes in a push to capitalise on dramatic advances inDN

A、forensic science. The advent of new ways to collectDN
A、from items at crime scenes, coupled with powerful analytical tools, has made it possible to obtainDN
A、profiles of suspects from undetected crimes or cold cases committed nearly 20 years ago, according to a Home Office spokeswoman. The operation has already identified 42 suspects.
The reviews focus on serious, often sexual offences and encompass at least 451 crimes committed between 1989 and 1995. Forensic scientists are returning to items of evidence stored at the time, from scraps of clothing to microscope slides holding just a few cells obtained from victims.
This week, scientists at the Forensic Science Service, which manages the police nationalDN
A、database, used the pioneering technique of familial searching to help convict James Lloyd, a shoe fetishist who pleaded guilty to six sexual assaults at Sheffield crown court.
The conviction came after scientists recoveredDN
A、from a 20-year-old sperm sample held on a microscope slide. While theDN
A、did not match anyone on theDN
A、database, scientists searched again for similarDN
A、profiles and found a close match with his sister.
The high-profile success follows the first use of a new intelligence tool known as pendulum list searching (PLS) which led to the conviction last month ofDuncan Turner for a sexual assault inBirmingham inAugust 2005. Scientists working on the case found a mixture ofDN
A、from different people on a pair of sunglasses found at the crime scene. They used PLS to generate a list of theoreticalDN
A、profiles that could make up the mix. Some 500 pairs of theoreticalDN
A、fingerprints were entered into the database, and one matched Turner. The FSS ploughed a further ￡ 6m into research last year and more powerful and precise techniques are in the pipeline.
Part of the push to review cold cases of sexual assaults comes from the development of a technique called Fish, or Fluorescent In Situ Hybridisation, which allows forensic experts to identify and pluck just a few male cells from a swab of female cells taken from the victim. The technique identifies male cells by dyeing green only those carrying the male Y chromosome. Once they are stained, another new tool, laser microdissection, is used to cut them out and collect them, so a full profile can be obtaineD、
Jim Fraser, a forensic scientist who served as an expert witness in the case of Michael Stone, who was convicted of a double murder in Kent in 1996, said advances inDN
A、science had already led to suspects being identified beyond the grave and would continue to become more powerful. "The long arm of the law is getting considerably longer-there’s really no hiding place now," he saiD、
According toCathy Turner, a consultant forensic scientist at the FSS, the rapid advances inDN
A、technology have transformed the role of forensic scientists. "We’ve gone beyond corroborating allegations to usingDN
A、and other techniques to provide fresh intelligence," she saiD、The swelling of the police nationalDN
A、database, which now holds profiles for 3.5m people, has in the last five years quadrupled the number of cases in whichDN
A、is useD、It provides police with some 3,000 matches to suspects every month. The nationalDN
A、database has been criticised by privacy groups, who fear the privatised database could potentially be misused, but for police forces it is an invaluable resource, saidDr. Fraser. "None of this evidence is infallible, irrefutable or unarguable.But it’s pretty much the best evidence that’ll ever be presented to the criminal justice system by some considerable way," he saiD、
Explain the sentence "The long arm ot7 the law is getting considerably longer" (par
A、7).