The British Transport Police (BTP) has referred two of its detectives involved in the case of double killer and rapist Simon Levy to the policing watchdog.

The force said the voluntary referral to the Independent Office of Police Conduct (IOPC) relates to an investigation conducted into two sexual assaults by Levy on the London Underground in October 2024.

The BTP said: "It's in the public interest for independent and objective scrutiny to be applied, and we will fully co-operate with the IOPC's independent investigation."

Levy, 40, was arrested by BTP officers in November 2024 over the previous month's Tube assaults but was bailed to return to custody in January, before this was extended twice until May 2025.

An IOPC spokesperson said: "During this period, Levy committed multiple further sexual assaults on trains, and other serious offences including murder and rape."

He committed a violent rape in January 2025, and killed Carmenza Valencia-Trujillo, 53, in March of that year. He murdered Sheryl Wilkins, 39, five months later.

The watchdog said it had received the voluntary referral from the BTP on 12 August - two days after Levy was sentenced.

"The families of murder victims Carmenza Valencia-Trujillo and Sheryl Wilkins, and the woman who survived the rape attack have been notified of our investigation," the IOPC spokesperson added.

Two Metropolitan Police officers are also being investigated by the IOPC over their handling of the case.