AVENTURA, Fla. -

Police say a man has been charged with first-degree murder in the death of a man at Aventura Hospital.

Aventura police said Alexander Jackson, 31, was admitted to the hospital Thursday and placed in a room with the victim, identified as 32-year-old Raul Alexander Rios.

Police said Rios was found on the floor of the room, unresponsive, by a witness. After efforts were made to revive Rios he was pronounced dead.

Jackson was found in the bathroom taking a shower a short time later.

The witness told officials at the hospital that Jackson told her he had done something wrong. Police said Jackson then later admitted to killing Rios by strangling him with his hands and a bed sheet.

The Miami-Dade County medical examiner's office ruled Sunday that Rios died as a result of ligature manual strangulation, just five days after his 32nd birthday.

Rios' sister, Francis Paloumbis told Local 10's Neki Mohan that her brother was a kind, gentle soul who was very introverted.

She says Rio was admitted to the hospital for depression, and has struggled with mental illness since he was a teenager.

Jackson is being held without bond.