Lithuanian officials have transferred French rock singer Bertrand Cantat from a prison hospital to a prison cell as they continue the investigation into his role in the death of actress Marie Trintignant.

Officials approved the move following improvement in Cantat's mental state. Prosecutors in the capital, Vilnius, filed charges last week against the lead singer of the French band Noir Desir for the beating death of the French actress, the singer's girlfriend.

Cantat allegedly inflicted head injuries on Trintignant, 41, during a conflict in a Vilnius hotel. Her family had her flown to Paris, where she died of the injuries earlier this month. The actress was in Lithuania shooting a film about the life of French writer Colette, which was being directed by her mother, Nadine.

Cantat has admitted being drunk and arguing with Marie, but called her death a horrible accident.