Four times between the winters of 2002 and 2005, a blue-eyed man wearing a ski mask and dark clothes crept quietly into the bedrooms of women in Bloomington, Ill., and raped them.

He told the women _ all in their 20s and single _ that he'd studied them, tracking their habits. He threatened one woman's family if she resisted, reciting their address lest she doubt he knew where to find them.

"I've been watching you," prosecutors say the rapist told another victim as he held a knife to her throat on a December night in 2002.

On Monday, jury selection is expected to begin in the trial of the man prosecutors say was the attacker: Jeff Pelo, a 17-year veteran of the Bloomington Police Department and married father of three.

Pelo, 43, who has pleaded not guilty, faces 28 counts of aggravated criminal sexual assault and four counts of home invasion. If convicted of all the charges, he could spend the rest of his life in prison.

His lawyers have argued that police have held the wrong man behind bars the past 22 months.

They say the charges are based on shaky identifications from women who saw only a man in a ski mask in their darkened bedrooms and who were asked more than a year later to identify him.

Prosecutor Mark Messman and defense attorney Mike Rosenblat of Chicago declined to discuss evidence or other details of the case as they prepared for trial, saying they didn't want to further complicate the process of seating a jury.

The rapes were scattered over 26 months, the first occurring in December 2002, the next in April 2003 and the last two in January 2005. There was little initial indication that they might be connected, only speculation.

"There was talk, but it seems like anytime there was talk, something else would happen, would shift the focus away from it," Messman recalled.

But in December 2005, after an FBI report found strong similarities between the crimes, Bloomington police asked the public for help catching the man they came to believe was a serial rapist.

In June 2006, Pelo, a well-paid sergeant at the time, was arrested and charged with attempted burglary, after another woman called police to report a late-night prowler.

Police say that when an officer found Pelo on foot outside the house just after midnight, he tried to walk away until the officer drew his gun.

"He had a blank stare on his face," Officer David Ziemer testified during one court hearing. "I was yelling 'Stop!' and he wasn't complying with me. I thought it was going to be a deadly force situation."

Pelo finally did stop, and told the officer he was in the neighborhood looking for a house to buy his mother-in-law. The house where he was arrested wasn't for sale.

Pelo faced burglary and stalking charges, but a month later the other charges were added after three of the four women identified Pelo from photos as their attacker. Two of them also said his voice was that of the man who'd raped them.

Pelo has been in jail since, held on $1 million bond. He continued to receive his $81,000-a-year salary until he resigned last November.

After he was charged, his wife, Rickielee, told reporters: "I know without any doubt in my heart that my husband is completely innocent of all these charges."

Messman said there are inherent problems in convincing a jury that a longtime police officer is capable of the sort of vicious, calculated crimes Pelo is charged with committing.

That said, "There are things about him being a police officer that make it more likely that he did," Messman said.

Messman declined to elaborate, but court records indicate that investigators believe Pelo used personal information from police reports and databases to stalk the women.

Other evidence includes a bag containing a ski mask, rope and a pry bar that investigators found in the home where the Pelos lived when he was arrested. Police have said the gear appears to have been used in at least one of the attacks.

Another police search turned up pornographic images of bondage and rape on Pelo's home computer.

The FBI and State Police have tested a human hair found on a pillow case in the bedroom of one of the women, a hair attached to a piece of duct tape used to bind one woman, and cat hair found on the ski mask taken from Pelo's garage.

According to Rosenblat, none of those tests linked his client to the crimes.

"All of the results from the FBI and state crimes labs have excluded Mr. Pelo as a suspect," Rosenblat said during a court hearing last August.