A doctor pleaded guilty Wednesday to giving Matthew Perry ketamine in the month leading up to the Friends star's overdose death. Dr. Salvador Plasencia became the fourth of the five people charged in connection with Perry's death to plead guilty. He admitted guilt to Judge Sherilyn Peace Garnett in federal court in Los Angeles, the AP reports. Plasencia, 43, was to have gone on trial in August until the doctor agreed last month to plead guilty to four counts of distribution of ketamine, according to the signed document filed in federal court in Los Angeles. He had previously pleaded not guilty, but in exchange for the guilty plea, prosecutors have agreed to drop three additional counts of distribution of ketamine and two counts of falsifying records.