Serena Perry was found in the hospital's amphitheatre. (Courtesy of Castle Funeral Home)

The female patient at the centre of a suspicious death at the Saint John Regional Hospital last week was under the care of the psychiatric unit, CBC News has confirmed.

The body of Serena Perry, 22, was discovered in the amphitheatre - another section of the facility.

Police are still refusing to comment on the case, except to say they have no one in custody.

But CBC News has learned the investigation focuses on two male suspects, who were also patients in the psychiatric unit.

The suspects, aged 17 and 18, were questioned by police, then returned to the psychiatric section, where they remain.

The unit includes patient rooms that can be locked down.

It has been alleged Perry and the two males in question were captured on hospital security cameras walking together some distance from the psychiatric unit before her death, which occurred sometime between Tuesday night and early Wednesday morning.

Many patients in the psychiatric unit are free to come and go, just like anyone else in the hospital. They can leave the unit to go for a smoke, visit the cafeteria, or just to stretch their legs.

Horizon Health Network officials have said patient safety is not at risk. (Connell Smith/CBC)

Horizon Health Network officials have said only that there is no risk to patient safety and that it’s business as usual at the province’s largest hospital, which thousands of people pass through every day.

The cause of death has not been released.

The major crime unit continues to investigate.

Horizon Health is co-operating with the police investigation and conducting its own review, officials have said.

It’s unclear whether there will be a coroner’s inquest.

A civil suit would depend on whether "standard of care” was met by the hospital and its staff, said Fredericton lawyer Pete Mockler, who has experience with health care lawsuits.

Patients are placed under different standards of care, depending on their diagnosis, he said. So there would be a set of protocols in place for each patient.

“You would want to go to the hospital protocols, particularly the protocols, practices and procedures that exist in the psychiatric ward, nursing protocols and the physician protocols, all of them as they relate to the question of leaving a psychiatric patient unaccompanied, or allowing psychiatric patients to leave the premises whether it's by themselves or with other psychiatric patients,” he said.

Perry mourned

Perry’s family declined to comment Wednesday after meeting with police at the station.

Police were called to the hospital at 12:20 a.m. on Wednesday, Sgt. Glenn Hayward has said.

"The investigation thus far has gleaned many interviews, forensic collection and analysis, pathology, and technical support," Hayward said.

Police have not revealed the victim's name at the request of the family.

Perry is described in her death notice as being “extremely outgoing,” and “very kind and caring to all.”

Mourners who signed her online guestbook describe her “beautiful smile, inquisitive mind and playful nature.” They say she was a “sweet and loving girl.”

Perry is survived by her parents, Rose Perry and Ken Hayward, two sisters, a brother, and other extended family members.