Police are investigating the possibility that the death of one inmate and hospitalization of three others in the Barton Street jail Wednesday was because of bad heroin.

Police say there have been six incidents in 24 hours of medical emergencies after the use of what was thought to be heroin.

"Is the heroin connected to this [the jail] death? Maybe," said Sgt. Terri-Lynn Collings of Hamilton police.

"We have to make that determination through a post-mortem," Collings said. "Based on the information we have, we're looking at it as a possibility."

Police are treating the death as suspicious, Collings said. The homicide squad has taken over the investigation.

"We're not aware of any weapons being used and there was no fight," she said.

Ontario NDP leader Andrea Horwath told CBC Hamilton she'd be surprised if the work stoppage at the facility coupled with overcrowding didn't contribute to the death.

"Does it take someone dying to shine a light on the problems at the Barton Street Jail and across the Ontario justice system?" she asked.

Horwath, the MPP for Hamilton Centre, said she is hoping for a full coroner's inquest into the death so that all factors can be examined.

"A person lost their life and that's something we never want," she said. "We need to figure out to what extent the last couple of weeks have played into this situation at the jail."

An inmate was found dead at the jail on the day guards returned to work for the first time in four weeks.  

The man was found around 6 a.m. Wednesday morning, said Dan Sidsworth, vice-chair of the Ontario Public Service Employee Union (OPSEU) corrections division. 

Three other inmates in the same unit also required medical attention, said Brent Ross, spokesperson for the Ministry of Community Safety and Correctional Services

"Given this matter is under investigation, it would be inappropriate to comment further," he said.

Hamilton defence lawyer Beth Bromberg told CBC Hamilton she had planned to go into the jail Wednesday to see clients, but was told she couldn't get in.

"This is a very big deal," she said, adding that she has no idea when she might be allowed access. "I have clients I need to see."

Barton Street jail guards walked out on Aug. 13 after a piece of metal on the fourth floor went missing. Guards wanted to search the facility wearing safety vests but jail management turned down the request.

Managers from across the province were called in to staff the jail.

After extensive discussion over four weeks with the Ministry of Community Safety and Correctional Services the guards returned to work Wednesday morning.  

Guards wore vests as they searched the jail Wednesday, Sidsworth said.

The death occurred in an area of the jail that was still under the control of  managers.

The incident is an example of the increasing violence in Ontario jails, Sidsworth said. It is the second homicide in an Ontario correctional facility this year.  

"Our thoughts and hearts go out to the family of the deceased inmate," he said. "This is a very serious situation, and not something we like to see. Inmate health and safety is a concern of ours as well."  

David Lane, executive director of the John Howard Society of Hamilton, says it wouldn't be far fetched for the work stoppage to be a factor in drugs being smuggled into the prison.

"I don't think it would be unfair to say it increased the risk," he said. "For things to go on this long just adds to the tension in the prison."

"This past month has just had a horrendous impact on the inmates themselves."