Paul Manafort’s former son-in-law, real estate developer Jeffrey Yohai, has agreed to plead guilty in connection with a criminal investigation in Los Angeles, multiple sources familiar with the investigation said Thursday.

Special counsel Robert Mueller and his team have been focusing for the past six months on Yohai, Manafort’s partner in four California property deals that failed and were placed in bankruptcy. Manafort’s holding company, MC Brooklyn Holdings, also bought a brownstone in Brooklyn, New York, in December 2012 for $2,995,000 that was brokered by Yohai, real estate postings online show.

It not yet clear whether Yohai’s plea deal is with the special counsel’s office or with federal prosecutors in California.

The criminal information and plea agreement detailing Yohai’s alleged crimes and any terms of his cooperation with authorities were not made public.

A sentencing date was not yet known. The public defender in Los Angeles did not immediately respond to a request from NBC News for comment.

Manafort, President Donald Trump’s former campaign chairman, is facing trials in two criminal cases brought by Mueller. He has pleaded not guilty in both cases. Yohai was divorced from Manafort’s daughter Jess last summer.

A federal judge in Washington on Tuesday declined Manafort's request to throw out one of the cases against him, saying the charges were "squarely" within Mueller's orders to investigate any links or coordination between the Russian government and individuals associated with Trump's campaign.

A federal judge in Virginia hearing Mueller's other case against Manafort cast doubt earlier this month on the special counsel's authority to bring bank fraud charges to trial and accused Mueller of squeezing Manafort to get information that could lead to Trump's impeachment.