ROME -- Police have released one of the men arrested as a suspect in the killing of a University of Washington student's roommate in Italy.

The man, Diya ("Patrick") Lumumba, is the owner of a pub in the town of Perugia, Italy. His lawyer said there's no evidence linking him to the case.

Police continue to hold UW student Amanda Knox and her Italian boyfriend. Knox had claimed that Lumumba killed her roommate, Meredith Kercher.

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Amanda Knox and her Italian boyfriend.

Lawyers for Knox and her boyfriend say they are innocent.

New suspect arrested in Germany

Meanwhile, a new suspect, an Ivorian man, was arrested Tuesday in Germany as police continue to investigate the killing.

An investigator in Perugia told The Associated Press that 21-year-old Rudy Hermann Guede was arrested in Mainz. He had been traveling by bus from the western German city to southern Germany.

More: New lead raises hopes for other suspects in student slaying

Guede is the fourth person to be arrested in the killing of 21-year-old Kercher. Police said she was stabbed to death fighting off a sexual assault.

Background: Knife used in murder owned by UW student's boyfriend

Her body was found November second in the apartment she shared with Knox in Perugia.

Also: Mother visits UW student in jail

Guede was arrested a day after police said he was being sought in the case. According to Italian news reports, a bloody fingerprint on Kercher's pillow and on toilet paper led investigators to Guede.