One week after placing CEO Clay Siegall on leave, cancer drug developer Seagen announced Monday that its cofounder and longtime leader has resigned as he faces an allegation of domestic violence.

Felix Baker, formerly Seagen’s lead independent director, will take Siegall’s place as chair of the board, while Seagen Chief Medical Officer Roger Dansey will continue as interim CEO, as previously disclosed. The company is beginning a search for a permanent successor.

“As we move forward, the Board has great confidence in the leadership of Roger Dansey, the senior management team and the nearly 3,000 employees to continue Seagen’s impressive growth trajectory,” Seagen said in a Monday statement announcing Siegall’s resignation.

His exit comes as Seagen conducts an investigation into an April 23 incident at the executive’s Seattle-area home that led to his arrest on charges of fourth-degree assault. Seagen didn’t acknowledge the events or Siegall’s arrest publicly until May 9, when it announced the CEO was temporarily on leave.

Seagen said that Siegall’s departure was not driven by the findings of its investigation.

Around 4 a.m. on the morning of April 23, local police in Woodway, Washington, received a 911 call from Siegall’s wife, who said Siegall had physically assaulted her after a night of dinner and drinks with three other couples. Two of the couples left earlier the evening before, while a younger couple stayed, according to a police report obtained by BioPharma Dive.

Statements collected by Woodway police said Siegall, who had gone to sleep earlier in the night, later argued with his wife, grabbed her and shoved her to the ground. Siegall’s wife had visible bruises on her arms and face when officers arrived, and she later noted more on her legs and hips, the report said. Siegall’s wife told police she was afraid for her life.

The husband of the younger couple also called 911 following the alleged altercation between Siegall and his wife.

Siegall told police he didn’t touch his wife, but gave conflicting stories. Officers described him as drunk, and determined they had probable cause to arrest him. Siegall was released after more than a day in jail, during which he called his wife several times and “thanked her for the possibility that he may get fired and that she may have ruined his career,” according to an officer who overheard one of the calls.

It’s not clear when Seagen learned of Siegall’s arrest and didn’t answer specific questions from BioPharma Dive. Siegall led Seagen’s first quarter earnings call on April 28, updating analysts on the company’s business and answering questions.

In its May 9 statement announcing Siegall’s leave of absence, Seagen also said it had hired a law firm and formed a committee to investigate what it described as an “alleged incident of domestic violence.” At the time, Seagen said its CEO denied the allegation and told the company he was divorcing his wife.

“Seagen has high standards for employee conduct and condemns domestic violence in all its forms. We are treating these allegations with the utmost seriousness,” the company’s independent board said in a statement emailed to BioPharma Dive on May 12.

Siegall is one of the biotech’s longest tenured and highest paid executives. A former National Institutes of Health researcher and Bristol Myers Squibb executive, Siegall cofounded Seagen in 1998 as Seattle Genetics and led it through the more than two decades since.

The company won approval of its first medicine, the lymphoma drug Adcetris, in 2011 and has followed with three more since, making Seagen one of the industry’s most valuable companies. It employs about 2,700 staff and is the biggest biotech company in the Pacific Northwest.

Seagen isn’t consistently profitable, however, and faces questions about its growth as well as competitive pressures that have weighed on sales.

Siegall’s firing therefore comes at a key moment for Seagen, which awaits several upcoming clinical trial readouts.

The company will now be led by Chief Medical Officer Dansey, a former Merck & Co. executive who was involved in developing its top immunotherapy Keytruda. Dansey was named interim CEO on May 9 and will continue in that role while the company searches for a new, permanent successor.

Siegall is due nearly $19 million in severance compensation, according to Seagen’s most recent annual report, mostly due to accelerated stock payments. He made a similar amount in cash and stock last year.

Under a May 15 agreement between Seagen and Siegall, any severance payments will be deferred until March of next year. Should Siegall’s exit be determined to have been for cause before the end of 2023, Siegall will forfeit his rights to the money.

Siegall also recently resigned as chairman of the board of Umoja Biopharma, a privately held cancer biotech, at the request of the company.