Dutch citizen Joran van der Sloot has pleaded guilty to killing a 21-year-old Peruvian woman at his trial in Lima.
Mr Van der Sloot went on trial last week for the murder of Stephany Flores, whom he met at a Lima casino.
She was found dead in a hotel in the Peruvian capital on 30 May 2010.
Mr Van der Sloot is a suspect in the disappearance in 2005 of US student Natalee Holloway, 18, on the Caribbean island of Aruba. Her body has never been found.
Stephany Flores was murdered five years to the day after Natalee Holloway was last seen.
The prosecution in Lima accused Mr Van der Sloot of killing Ms Flores "with cruelty and ferocity" in a hotel after they met while playing poker.
By pleading guilty, the Dutchman should get certain benefits under Peruvian law, such as a reduced sentence. The three judges in the trial have 48 hours to pass sentence.
Mr Van der Sloot had told police that he killed Ms Flores after she found details on his laptop of his alleged connection to Natalee Holloway's disappearance.
He was arrested but never charged in that case, which was the subject of wide public interest in the US and elsewhere.