Robert Mueller, the former special counsel who led the investigation of Russian interference in the 2016 presidential election, has Parkinson’s disease, his family said in a statement to The New York Times on Sunday.

“Bob was diagnosed with Parkinson’s disease in the summer of 2021,” Mueller’s family told the outlet. “He retired from the practice of law at the end of that year. He taught at his law school alma mater during the fall of both 2021 and 2022, and he retired at the end of 2022. His family asks that his privacy be respected.”

The Times added that Mueller has recently had mobility issues as well as difficulty speaking, citing sources familiar with his condition.

His family’s disclosure comes as Mueller was served with a subpoena to testify before the House Oversight Committee on Tuesday as part of the panel’s investigation into the government’s handling of the Jeffrey Epstein case, given that the former special counsel served as FBI director from 2001 to 2013 when the disgraced financier was investigated for sex crimes.

“Because you were FBI Director during the time when Mr. Epstein was under investigation by the FBI, the Committee believes that you possess knowledge and information relevant to its investigation,” the subpoena letter read.