Tonight we look at DNA testing - invented by a British scientist 17 years ago - which has revolutionised the work of the police. Criminals who thought they had got away with it now face the long arm of DNA technology. DNA testing has helped to track down serial killers, while freeing scores of innocent people on death row in the United States - putting their criminal justice system in the spotlight. From its first successful application in a British murder case to the hunt for one of Italy's most prolific serial killers, this programme charts the rise of this extraordinary new technology.

Filmed exclusively during his fight for freedom, this episode centres around the amazing case of Chris Ochoa (above, centre with his defence team) who was convicted of the rape and murder of Nancy DePriest in a Pizza Hut in Austin, Texas, in 1988. When another man, Achim Joseph Marino, confessed to the crime in 1996, and DNA testing was used to back up his guilt, Ochoa was finally exonerated 13 years after his conviction. Richard Danziger, Ochoa's co-accused, is awaiting release but a severe beating from a fellow inmate, who mistook him for someone else, has left him with brain damage and he is currently still interned in the Skyview psychiatric prison in Rusk, Texas.

NYPD Blue

Pearl, 12.55am

It's an action-packed episode as Sipowicz (Dennis Franz), Sorenson (Rick Schroder, above), Russell (Kim Delaney) and Kirkendall (Andrea Thompson) are dispatched to investigate the murder of a woman whose body was dumped in an excavation hole. The ID found in the victim's wallet identifies her as Elvira Iglesias. Iglesias' mother identifies the body as that of her daughter, but she is acting strangely and is in possession of a life insurance policy on Iglesias' life for US$5,000.

Meanwhile, Lt Fancy (James McDaniel) is dodging bullets at a stakeout operation to confiscate illegal guns.

Bodybuilding: World's Strongest Man

Star Sports (cable), 6pm

Star Sports (satellite), 4pm

Tonight's programme shows some of the most demanding tests of strength on television.

On October 5, the world's most muscular people convened at a resort near Livingstone, Zambia, for the ultimate bragging rights among the gym set: the International Federation of Strength Athletes' World's Strongest Man and, for the first time, the World's Strongest Woman titles.

Tonight, 33 men and 10 women focus, approach and then attempt - with eye-bulging determination - the contest's preliminary round feats like the carry and drag, train pull, and Africa stone to supportive grunts of 'You can do it' and the mandatory, climactic 'Yeah!'.

Look out for defending world champion, the two-metre tall Janne Virtanen of Finland, and his nearest challenger, Svend Karlsen of Norway, the 145-kilogram 1997 winner and European title holder with a 154-centimetre chest. The World Muscle Power Champion, Hugo Girard, promises to impress for Canada, along with the European arm-wrestling champion and 1998 winner, Magnus Samuelson of Sweden. Watch out too for America's 2000 Hercules, Phil Pfister. In the women's event, his 1.62-metre, 78kg compatriot, Jill Mills (above), flipped 272kg tractor tyres and lifted beer kegs in her back yard in readiness for the likes of fellow American Robin Coleman and Finland's Heini Kovuniemi.