Yoni Alzam, the prisoner who died in his cell hours before he was supposed to testify at a murder trial, was poisoned, police said on Thursday. Petah Tikva Magistrate's Court authorized the publication of the information but placed a gag order on other details relating to Alzam's death, effective until March 13. Two weeks ago, the court authorized the police to disclose that two people visited Alzam just before he died and that detectives were investigating Shimon Zirhan in connection with his death. Alzam was murdered in December 2005 just before he was scheduled to testify against Zirhan for the latter's part in the death of crime figure Hanania Ohana in 2003. Zirhan allegedly shot and killed Ohana in front of his wife and child in a Petah Tikva parking lot. Alzam was sentenced in November to life in prison for his involvement in Ohana's murder, but as a state's witness he received 24-hour protection from prison guards and was held in a private cell so that he could be kept separate from the general prison population. An autopsy conducted at the L. Greenberg Institute of Forensic Science found a chemical substance in Alzam's body, leading police to believe that his death was unnatural. At an early stage in the investigation, the case was taken up by the police's elite Serious and International Crimes Unit (SICU). "This is a complicated and sensitive case since Alzam was murdered in his cell in a high-security prison where he was supposed to be under 24-hour surveillance," police said in December.