CBS News correspondent Sabina Castlefranco reports this fingerprint apparently does not belong to any of the three suspects currently being held in the case.
The same person's prints were also found on toilet paper in the house where the body of Meredith Kercher was discovered by police on Nov. 2, in the Italian university town of Perugia, said lawyer Francesco Maresca. Kercher, 21, had been sexually assaulted and fatally stabbed.
Speaking by phone from Florence, Maresca did not know whether the prints belonged to the potential new suspect in the case, but said they did not belong to any of the three suspects now jailed in the probe.
Milan daily Corriere della Sera reported that one of the prints, on Kercher's pillow, was that of a man's thumb, but Maresca said he had no details about the prints, including whether they were believed to be those of a man.
British and Italian news reports indicate that Italian authorities have issued a fourth arrest warrant in the case, with reports that the fourth suspect is a man from the Ivory Coast with a criminal past.
Castlefranco said authorities are being tight-lipped about the suspect's identity; there is the possibility that he may have already left the country.
Lawyers for the three suspects previously detained said the discovery bolsters their appeals to a court to review the judge's Nov. 9 ruling jailing their clients. A date for a new hearing on the detentions is expected to be announced this week.
Her 20-year-old American roommate, Amanda Marie Knox; Knox's 23-year-old Italian boyfriend, Raffaele Sollecito; and a Congolese pub owner, Diya "Patrick" Lumumba, 38, are being held in a Perugia jail as suspects.
No charges have been filed. But the Italian judge who upheld the suspects' detentions has said there were "serious indications of guilt" that warranted keeping them behind bars for up to a year while the investigation continues.
All three suspects have denied involvement in the killing.
Lawyers for the three suspects submitted motions to a court to review the detentions late last week. By early this week, prosecutors must respond by submitting the results of their investigation so far. Also this week, the court is expected to set a date for a hearing as to whether the detentions are justified, the attorneys said.
The lawyers praised indications that investigators were turning their attention to another suspect after bloody fingerprints were discovered on Kercher's pillowcase and on toilet paper in the house that did not match those of any of the three jailed suspects.
"I'm convinced this is an open case," said Carlo Pacelli, Lumumba's lawyer. He said that he hopes the hearing would confirm that his client had nothing to do with the slaying; Lumumba has maintained he was at his pub, not in the apartment, on the night of the slaying.
Tiziano Tedeschi, attorney for suspect Raffaele Sollecito, said the lead on the pillowcase traces was "good news."
Tedeschi said investigators knew from the beginning that there were such traces and that Meredith was found with hair clutched in her hands. He said investigators should have focused on identifying the DNA from those samples rather than detaining his client in haste.
"This is the first suspect, not the fourth," he said of the new investigative lead. "They should have immediately focused their attention on this subject, and then if there were others."
"They (prosecutors) didn't want to find the truth; they wanted to close the case and make a 'bella figura,'" because the case was in the international spotlight, he said in a phone interview.
Luciano Ghirga, Knox's attorney, said the reported identification of a new suspect changed little for his client. He noted that Knox had never mentioned any such person in her two declarations to prosecutors.