The police and crime commissioner for Cambridgeshire and Peterborough has resigned after being referred to the police watchdog.
Conservative Jason Ablewhite was elected to the role in 2016.
A statement released by his office said: "Jason Ablewhite has today... tendered his resignation as police and crime commissioner."
It confirmed he had been referred to the Independent Office for Police Conduct (IOPC) but did not say why.
Mr Ablewhite's office added: "It would be inappropriate for us to make any further comment."
The IOPC said it had "started an independent investigation following a referral about a public complaint into the conduct of the police and crime commissioner for Cambridgeshire".
"The investigation is in its early stages and it is too soon to speculate on the outcome."
An acting commissioner will be appointed and serve until the next scheduled election for the post in May 2020, a spokeswoman for the Cambridgeshire Police and Crime Panel, said.
Mr Ablewhite is a current member and former leader of Huntingdonshire District Council.