The cellphones of two defendants on trial for the murder of a British student remained inactive the night of the killing in Italy, witnesses testified Friday.

PERUGIA, Italy — The cellphones of two defendants on trial for the murder of a British student remained inactive the night of the killing in Italy, witnesses testified Friday.

Investigators said that because the cellphones were turned off, it was impossible to trace the defendants’ whereabouts when Meredith Kercher was killed by a stab wound to the neck in Perugia.

Defense lawyers contend that the cellphone data was inconclusive.

Friday’s session in the trial of University of Washington student Amanda Knox and her former Italian boyfriend, Raffaele Sollecito, was largely devoted to analyzing evidence recovered by police and telecom experts from the cellphones of both the victim and the defendants.

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Both Sollecito and Knox, who was Kercher’s roommate in Perugia, have denied wrongdoing in the case. Both have said they were not at the Perugia home the evening of Nov. 1, 2007, when Kercher was killed, though Knox gave conflicting accounts during earlier police questioning.

Police inspector Letterio Latella, who analyzed the data, said the defendants’ cellphones showed no activity on the night of the crime. He said Sollecito’s cellphone was inactive between 8:42 p.m. Nov. 1 and 6:02 a.m. Nov. 2, when a text message sent the night before by his father popped up. The inspector said there were no reported glitches in the network that night.

The lack of phone activity for almost 10 hours was unusual, the investigator said, when compared with Sollecito’s cellphone use over the previous month.

Knox’s cellphone was inactive between 8:35 p.m. Nov. 1 and 12:07 p.m. Nov. 2, when a call was placed to Kercher’s British number, Latella said, citing operator records.

Giulia Bongiorno, a lawyer for Sollecito, said communications companies’ records were not conclusive, as they did register attempted calls. She said Kercher’s cellphone showed three attempted calls Nov. 1 that were not detected by the companies’ registries.

Kercher’s body was found on the morning of Nov. 2 in the apartment she shared with Knox. Her two cellphones were discovered in a neighbor’s garden.

The 21-year-old woman is believed to have died between 9 p.m. and 11 p.m. Nov. 1, based on the autopsy and the accounts of friends with whom she had eaten dinner that night, according to court documents.

Prosecutors allege that Kercher was killed during what had begun as a sex game. They have won the conviction of a third person in the case, Rudy Hermann Guede of the Ivory Coast, who denied wrongdoing during a separate trial last year. He was sentenced to 30 years in prison.

Sollecito, 24, has said he was at his own apartment the night of the murder. He said he was working at his computer, though one witness testified there was no sign of Sollecito using his computer during the hours Kercher was killed.

Both Sollecito and Knox, 21, have been in jail in Italy since shortly after the murder.

Phone records show Knox exchanged text messages with the Congolese owner of a pub where she used to work part time, witnesses said. She sent a message at 8:35 p.m. to Diya “Patrick” Lumumba, saying: “Sure. See you later. Have a good night!” according to Simone Tacconi of the telecommunications branch of Rome police. The message was in Italian.

Lumumba was detained for two weeks in November 2007 after he was implicated by Knox. He has since been cleared and is seeking defamation damages from Knox.

On Thursday, police said intruders had broken into the house where the murder occurred, the second time in a month. Police on a routine inspection Thursday noticed a window had been broken.

In February, intruders ransacked the Perugia house and left four kitchen knives and some candles in various rooms. This time the intruders left nothing but moved things around, local media reported.