CTV News has learned Halifax Regional Police is launching an internal investigation into the actions of three constables following the death of a man in custody last year.

Corey Rogers was arrested for public intoxication at the IWK Health Centre the night of June 15, 2016. The 41-year-old man was found unresponsive in a police cell three-and-a-half hours later. Attempts to revive him were unsuccessful.

His mother, Jeannette Rogers, says Corey was wearing a spit hood at the time and has been told his cause of death was asphyxiation. She also says an arresting officer put the spit hood on her son in the vehicle parked at the police station.

Jeannette has now received a registered letter from the sergeant-in-charge of professional standards for Halifax Regional Police, in which he says he is commencing an internal investigation under the Police Act.

He also says a separate internal investigation involving two booking officers already charged with criminal negligence causing death has been suspended until the court process has concluded.

Jeanette says she is encouraged by this development.

“Hopefully it will end in them being reprimanded to some degree because in my view they were culpable in the situation,” she says.

A CTV News investigation previously revealed Halifax Regional Police changed its regulations on spit hoods following Corey Rogers’ death. Documents obtained from Halifax Regional Police through the Freedom of Information Act state that since Rogers’ death, the force issued an order to all ranks regarding the use of spit hoods.

Jeannette Rogers still wants to see a full judicial review to ensure the safety of intoxicated people in police custody. She's also calling for a ban on the use of spit hoods.

With files from CTV Atlantic’s Kelland Sundahl.