EX-CON WILL BE TRIED IN SLAYING MAN, 37, ACCUSED OF PROSTITUTE MURDER.

Byline: Charles F. Bostwick Staff Writer

LANCASTER - A registered sex offender has been ordered to stand trial on charges he raped and murdered a 40-year-old Lancaster woman who worked as a prostitute and was found beaten to death in 1999 on a desert dirt road.

Ronald Lynn Rook is accused of kidnapping, sexually assaulting or robbing four women who worked as prostitutes along Sierra Highway from 1999 to 2003, and of killing one of them, Twila Ann Martin, a mother of two who family members said tried but was unable to kick a drug addiction.

``Twila was a pretty tough girl by everybody's account and probably put up a fight,'' sheriff's homicide Sgt. Tim Miley said of detectives' speculation on why Martin was killed. ``That's our guess, but it's only a guess.''

After a two-day preliminary hearing, Antelope Valley Superior Court Judge Lisa Chung ruled there was enough evidence to try Rook on 12 of the 14 charges made against him.

Two rape charges were dismissed after one of the four women said she had sex willingly with Rook after he picked her up, but that Rook then pulled out a gun and robbed her of the money he paid her.

Rook, a 37-year-old ex-convict who got out of prison in 1997 after serving a sentence for assault with a firearm, was linked to Martin's slaying last year by an ongoing check of a DNA database containing samples from convicted felons.

Rook was arrested in November while working on a Santa Clarita assembly line.

The other three women's cases were linked to Rook after Miley reviewed Antelope Valley rape cases dating back to when Rook got out of prison.

Detectives also reviewed other local killings of women who worked as prostitutes - of which at least five were between 1994 and 1999 - but in every case where there was DNA evidence, it eliminated Rook as the killer, Miley said.

Detectives say they have no proof that a serial killer was responsible for the women's deaths. Drug-addicted prostitutes live dangerous lives, and are vulnerable to boyfriends, customers and drug suppliers, detectives said. Martin's body, clad only in a T-shirt and bra, was found Feb. 28, 1999, in the middle of a dirt road near Avenue L-8 and 15th Street East. She had been raped and severely beaten.

Martin had vowed to change her life. She married and moved to Ohio, but divorced soon after. Both of her children were taken away from her when she started using drugs again, friends said.

Investigators initially arrested an ex-convict friend of Martin whose home she had visited the morning before she was killed. But he was quickly cleared based on DNA evidence.

A Lancaster man convicted of kidnapping and raping prostitutes was investigated in the deaths of three women in 1996 and 1997, but DNA evidence cleared him in the killings.

Martin died while that man was in jail awaiting trial on rape and kidnapping charges, for which he was convicted and sentenced to 181 years to life in prison. Two of the other women died while Rook was in prison on the assault charge, records show.