Israel’s Ministry of Communications Director-General Shlomo Filber, a longtime associate of Prime Minister Benjamin Netanyahu, signed a deal on Tuesday night to become a state’s witness in a growing corruption investigation involving the Israeli premier.

Filber is expected to testify in what is being dubbed “Case 4000,” in which Netanyahu told him to provide regulatory benefits to the Bezeq telephone company in exchange for positive coverage of Netanyahu and his family from the Walla news site. Walla and Bezeq are both owned by Shaul Elovitch, who was also arrested in connection to the case.

In the deal Filber signed, he will give testimony against Netanyahu in exchange for a guarantee not to serve prison time.

Filber was appointed to head the Ministry of Communications while Netanyahu himself served as its minister from 2014 till 2017. The ministerial position was later given to Likud Party minister Ayoub Kara.

Netanyahu has firmly denied any wrongdoing in Case 4000, calling the investigation “part of the witch hunt against me and against my family which has been going on for years.” In a publicized video on Tuesday, he insisted that all decisions regarding Bezeq were made under professional oversight with legal supervision.

He also responded to allegations that he was involved in an offer made by family spokesperson Nir Hefetz to an Israeli judge that she would be promoted to attorney general if she helped to stop investigations against Netanyahu’s wife, Sara.

“I never asked Nir Hefetz about this, he never spoke to me about it, and you know what? I cannot believe he raised this possibility with anyone,” Netanyahu responded. The prime minister is not currently being charged with involvement in the scandal, but Hefetz was arrested.

Netanyahu has been hit by a number of corruptions charges in the last two weeks.

In Case 1000, Netanyahu and his wife are alleged to have received illegal gifts from billionaire benefactors for 20 years at a total of $282,000. The primary giver, Arnon Milchan, allegedly received help from Netanyahu in the form of favorable legislation, visa arrangements and business advantages.

In Case 2000, Netanyahu is alleged to have sought a deal with Israeli daily Yediot Ahronot’s publisher Arnon Mozes, whereby Netanyahu would help weaken daily Israel Hayom—owned by American former campaign supporter Sheldon Adelson—in exchange for favorable coverage.

An additional case, Case 3000, has investigated possible corruption regarding a multibillion shekel purchase of submarines and sea vessels from a German company. Netanyahu himself has not been named as a suspect, but a number of associates, including two of his personal aides, have been arrested.

Netanyahu has emphatically denied any part in the cases under investigation and has condemned his rivals for attempting to stoke suspicion against him in order to take political power.