The House Ethics Committee announced Wednesday that it will extend its inquiry into Rep. John Conyers's (D., Mich.) payments to his former chief of staff.

The committee said it needed more time to review a report by the Office of Congressional Ethics, the Associated Press reports. The report suggests that there is "substantial reason" to believe that Conyers paid his chief of staff, Cynthia Martin, for work she did not perform.

In April of 2016, Conyers claimed to have placed Martin on unpaid leave, after she pleaded guilty to receiving stolen property. However, the ethics office said that she was paid over $13,000 a month through August of 2016.

Investigators were told as early as June of 2016 that she no longer worked in the office; she was only officially fired in October.

A spokesman for Conyers said that he has worked to comply with all rules, and is cooperating fully with the ethics committee.

The ethics committee will also be extending its investigation into Michael Collins, chief of staff to Rep. John Lewis (D., Ga.). The Office of Congressional Ethics has suggested there is reason to believe Collins improperly served in two roles, acting both as Lewis's chief of staff and as treasurer of his 2016 election campaign. He received $167,500 in the former position, and $55,000 over two years in the latter.

Conyers is the longest serving member of Congress, having represented his Detroit congressional district for 27 terms, since 1965.