The ex-con bouncer who has emerged as the lead suspect in the sex-assault murder of grad student Imette St. Guillen is now being eyed in a string of rapes in Queens and Long Island, law-enforcement sources said yesterday.

The cops' focus on Darryl Littlejohn in the sex attacks surfaced after one victim watched the past day's TV footage of investigators searching the bouncer's blue minivan parked in his driveway — and phoned police to tell them it appeared to be the vehicle in which she was raped, sources said.

The woman was attacked in Queens late last year, part of an apparent pattern of at least three rapes in which the victims all gave similar descriptions of their attacker. A second rape also occurred in Queens, and the third took place in Nassau County, the sources said.

Littlejohn, 41, was moved to Rikers Island yesterday to await a hearing on whether he would be returned to prison for violating his parole on an armed-robbery rap.

- Raw Data: Transcript of Littlejohn's most recent parole hearing(pdf)

As an ex-con, he wasn't supposed to be working security at The Falls bar in SoHo, where he was reported last seen tossing out a drunken St. Guillen early Feb. 25. Her body was found hours later in weeds off the Belt Parkway in Brooklyn.

Littlejohn has maintained his innocence in St. Guillen's slaying.

Investigators yesterday continued combing the hardened criminal's Queens home for clues as they try to build a case against him. Their latest haul included bags marked with blaring orange "Biohazard" stickers and stuffed with such items as military green pants, a black wool hat and Timberland boots.

They also towed away the minivan in Littlejohn's driveway — a dark-blue Dodge Ram 250.

In addition to that van, probers focused on his Ford Windstar, parked two blocks from the house, which matches a description of a vehicle spotted near where St. Guillen's body was dumped.

The van was missing a row of seats, and cops yesterday removed a similar row of seats from Littlejohn's house.

While Littlejohn insists he was nowhere near the remote street in East New York where St. Guillen's body was found, police say cellphone records put him nearby shortly before her corpse was discovered.

Sources say at least one of the calls from his cellphone was made to a girlfriend, who later told cops the conversation was inconsequential.

An apparent ladies' man, Littlejohn's personal phone book was filled with women's numbers — including ones for "Babymomma 1" and "Babymomma 2," the sources said.

But one neighbor said he could be abusive with his women, claiming that he openly hit one girlfriend in front of his home about two months ago.

"I saw him slap her. He hit her, and she fell onto the door," said the 28-year-old woman who spoke on condition of anonymity. "He's very intimidating. The way he walks, like it's all about him. I didn't like his aura."

The woman said Littlejohn would stroll around in jackets emblazoned with "FBI," "Bounty Hunter" and "U.S. Marshal" over Army fatigue pants and with a pair of handcuffs hanging off his waist.

He has told cops that when St. Guillen — a forensic-science graduate student major at John Jay College — was still at the bar one the fateful night, she jokingly told him she was an FBI agent, and he responded that he was a U.S. marshal, law-enforcement sources said.

But other neighbors painted the picture of a guy who struggled for much of his life and had hoped to turn it around.

"He used to sell drugs, but he got out of that. He was straightening up his life," Gregory Jones said. "He was never a violent man. He just likes fast money."

Neighbor Jeffrey Katz, 38, called Littlejohn "a quiet guy.

"He used to date a girl I know. She said he was always a happy person. He never got angry," Katz said.

After Littlejohn's early release from prison on the robbery rap two years ago, Katz said the bouncer told him, "I just want to relax and take care of my kids. I don't want to go back there [to prison] again.

"He was trying to get himself together," Katz said.

Sources say the 5-foot-7, 200-pound bouncer had argued with 25-year-old St. Guillen just before her disappearance.

He had been ordered to toss her from the bar by Danny Dorrian, a bartender — and not the co-owner, his brother, Michael J. Dorrian, as reported in yesterday's Post, witnesses told police.

Sources say Danny Dorrian told cops he then heard an argument and a muffled scream. Danny Dorrian did not return a call to his cellphone yesterday.

Littlejohn insists he just escorted St. Guillen out and that she walked away alone.

The barroom heavy was hauled in for questioning Sunday, but only after Danny Dorrian finally came forward with a full account of what he saw that night. He spoke to police three times, but it wasn't until the last time that he finally acknowledged he was bartending that night and ordered Littlejohn to remove her from the bar, sources said.

When questioned by The Post last week, Danny Dorrian, 33, referred to himself as a "lowly day manager" — and said he wasn't even working the morning St. Guillen disappeared.

Under the law, a person is under no obligation to tell cops what he knows, legal experts said. However, if it can be proven that the person knowingly gave false information to police, it's possible they could face obstruction of justice charges.

Cops are working on a theory that Littlejohn went with St. Guillen and either raped or tried to sexually assault her, then panicked and killed her when she fought back.

St. Guillen's strangled body was found bundled in a cheap floral-print blanket, her hands and feet tied with wire and her face wrapped in brown plastic tape.

Wire and tape similar to those found on her body have already been recovered from the basement of The Falls, sources said.

Cat hairs also were found on the blanket and tape across her mouth - and investigators were checking to see whether they match those from two cats living in the bar's basement.

When St. Guillen's body was recovered, her fingernails were partially torn off, indicating she had put up a fight, cops said.

Meanwhile, Littlejohn showed up for work the night after the murder with scratches on his neck, sources said.

Police already have his DNA to test against any recovered as evidence. He was required to provide it upon his release on parole in 2004.