The bouncer at the center of an investigation of the rape and murder of a graduate student is a suspect in a separate Queens sexual assault case despite the victim’s failure to identify him, law enforcement officials said.

Darryl Littlejohn appeared in a lineup yesterday. Although the victim could not positively identify him, investigators said there is physical evidence that is being examined linking the bouncer to the Forest Hills crime, which occurred October 16, 2005.

Littlejohn, 41, a convicted felon who has used nine aliases, is also suspected of kidnapping and raping a 15-year-old girl in Elmont in Nassau County on November 9, 2005.

As of last night, Littlejohn had not been arrested in the death of Imette St. Guillen, whose naked and bound body was found February 25. She was last seen alive at the Falls, a SoHo bar, at about 4 a.m. According to corrections officials, Littlejohn was being held on Riker’s Island on a parole violation.

Littlejohn has an extensive criminal record, beginning when he was 16. In 1980, he pleaded guilty to first-degree robbery, the Manhattan district attorney’s office said. Just more than a decade later, he served time as John Handsome, one of his aliases, for separate drug possession and sale convictions, as well as for armed bank robbery in 1995, court documents and corrections records show.

Littlejohn’s criminal background could spell possible legal and financial jeopardy for the bar’s owners, Michael and Daniel Dorrian, including license revocation and a fine of up to $10,000.

A spokesman for the State Liquor Authority said on Thursday that the authority is cooperating with police and is looking into whether the Falls could face charges for employing an ex-convict. The Dorrian family also owns Dorrian’s Red Hand on the Upper East Side.

Police declined to comment on possible charges, and the attorney representing Daniel Dorrian, who manages the Falls bar, also declined comment.