Colin Holt, 52, died in August 2010 at his flat in Goudhurst Road, Twydall, in Gillingham.
He had been arrested by Kent Police after he went missing two days earlier after being detained under the Mental Health Act.
He was handcuffed with his arms behind his back and laid in a prone position.
A post-mortem examination concluded he died of positional asphyxia.
PCs Maurice Leigh and Neil Bowdery were charged with misconduct in public office in September 2012, but were cleared following a trial at Maidstone Crown Court in May 2013.
The Independent Police Complaints Commission (IPCC) said both officers had a case to answer for gross misconduct.
A spokeswoman said the IPCC had sent a report to Kent Police.
"Kent Police has accepted our findings and can now commence misconduct proceedings," she said.
"It would not be appropriate to release our report in advance of those proceedings."
The jury returned a narrative verdict following the inquest at Archbishops Palace, in Maidstone.
Three police officers failed to comply with their duty of care when a mentally ill man died after being handcuffed, an inquest jury has concluded.