Relatives of some of the victims wept in the courtroom as the confession by Gary Ridgway, 54, was read aloud by prosecutors. "I killed so many women I have a hard time keeping them straight," he said in the statement. "I wanted to kill as many women as I thought were prostitutes as I possibly could."

Ridgway, a former truck painter, struck a plea bargain that will spare his life, in exchange for a confession and life in prison without parole. The deal has come under fire from some lawyers who say it could make it difficult for prosecutors to seek the death penalty in other cases.

Ridgway, known as the Green River Killer, began in 1982, targeting women in the Seattle area, many of whom were either prostitutes or runaways. Their bodies were initially dumped in and around the Green river, giving the killer his name. Others would later be found near ravines, airports and motorways. In many cases, he had sex with his victim before strangling her. The murders stopped in 1984 as abruptly as they began. But Ridgway later resumed killing, and yesterday admitted to two murders in 1990 and 1998.

"I placed most of the bodies in groups which I call clusters. I did this because I wanted to keep track of all the women I killed," he said in his statement. "I liked to drive by the clusters around the county, and think about the women I placed there."

In the Seattle court yester day, Ridgway was presented with the details of each murder, one by one, and was asked to confirm them.

He mostly killed women near his home, or in his truck not far from where he picked them up. "In most cases, when I killed these women, I did not know their names. Most of the time I killed them the first time I met them, and I do not have a good memory of their faces."

Explaining his motives for targeting prostitutes, he offered several reasons: "I hate most prostitutes, and I did not want to pay them for sex," he said. "I also picked prostitutes as victims because they were easy to pick up without being noticed. I knew they would not be reported missing right away, and might never be reported missing. I picked prostitutes because I thought I could kill as many of them as I wanted without getting caught."

Ridgway had been a suspect as early as 1984, when Marie Malvar's boyfriend reported that he last saw her getting into a pickup truck identified as Ridgway's. But he told police he did not know Malvar, and investigators cleared him. Later that year he also passed a polygraph test. It was only in 2001, thanks to advances in DNA technology, that a saliva sample taken from him in 1987 was matched to the bodies of three of his earliest victims, leading to his arrest.

"It was hard to sit there and see him not show remorse," said Kathy Mills, whose daughter Opal was 16 when her body was found in the Green river. The defence said Ridgway was sorry and will express that to the families at sentencing. His lawyer, Tony Savage, said the emotions came "in private, in emotional ways, in tears and in words... He feels terrible remorse."