The US Department of Justice (DoJ) has opened an investigation into Eric Swalwell following his resignation from Congress, according to a source familiar with the matter.

The news of a federal investigation comes days after the Democratic representative from California stepped down due to multiple allegations of sexual misconduct.

The DoJ has not publicly commented on its investigation.

Swalwell, a seven-term representative, was a frontrunner to replace Gavin Newsom as California’s governor until he became engulfed in scandal. He suspended his gubernatorial campaign and then resigned from Congress after the San Francisco Chronicle reported the account of an unnamed former staffer, who said he sexually assaulted her on two occasions. CNN published a similar account, which included claims from three other women who said Swalwell had sent them unwanted sexual messages.

On Tuesday, the day after Swalwell resigned, Lonna Drewes, another alleged victim, publicly came forward, saying Swalwell had drugged and raped her in 2018. Drewes spoke out at a press conference in Beverly Hills, saying the representative choked her and that she “lost consciousness” and thought she had “died”.

Sara Azari, a lawyer representing Swalwell, said in a statement earlier this week that he “categorically and unequivocally denies each and every allegation of sexual misconduct and assault that has been leveled against him”.

Azari did not immediately respond to an inquiry about the DoJ investigation on Thursday.

The Los Angeles sheriff’s office said this week it was investigating the 2018 allegations, and the LA district attorney’s office said its sex crimes division was working with law enforcement involved in the case. The Manhattan district attorney’s office said over the weekend that it was investigating a sexual assault allegation against Swalwell.

Swalwell, who was first elected in 2012, was facing the threat of expulsion from Congress when he announced his resignation, saying in a statement: “I am deeply sorry to my family, staff, and constituents for mistakes in judgment I’ve made in my past … I will fight the serious false allegation made against me. However, I must take responsibility and ownership for the mistakes I did make.”

The woman who spoke to the Chronicle said Swalwell began pursuing her soon after she was hired in 2019, at the age of 21. She said he twice sexually assaulted her when she was too intoxicated to consent.