The search continues for an inmate who escaped from an Ontario jail by disguising himself as his cellmate, an incident that has prompted authorities to launch an internal investigation.

Police allege 19-year-old Justin Kunz altered his appearance and then threatened his cellmate, who was due to be released, to be quiet when correctional officers entered their cell in the Elgin-Middlesex Detention Centre in London, Ont., on Wednesday morning.

Kunz, who's from London, was before the courts for offences including firearms possession, failing to comply with court orders, uttering threats and mischief. He now faces arrest warrants for personation, uttering threats and being unlawfully at large, police said.

The Ministry of Community Safety and Correctional Services said Kunz did not escape, but rather was "improperly released."

"To date no one has ever escaped on their own or with the help of others, from the Elgin-Middlesex Detention Centre," spokesman Brent Ross said in a statement.

"The improper release of any inmate from a correctional facility is unacceptable and the ministry takes its responsibilities in this area very seriously."

London police Const. Ken Steeves said even though the charges Kunz faces are serious, there's no indication the public is in danger.

"He was in possession of firearms in the past and we have seized them, so that's no longer a concern," he said. "We don't have any indication that he poses a threat to the community."

Steeves said the search for Kunz is still local, and anyone with information on his whereabouts should call London police or Crime Stoppers.

Monte Vieselmeyer, a corrections officer and chair of the Ontario Public Service Employees Union corrections division, said inmates being released are typically identified by managers in admitting and discharge offices, rather than corrections officers.

The managers check the inmate's identification card, background paperwork and ask questions such as birth dates, names of their probation officers, locations of their last court appearances to verify the inmate's identity.

"In this particular case, was that done? I don't know," Vieselmeyer said, adding that staffing shortages have plagued Ontario jails recently, prompting heightened tensions between guards and inmates and frequent lockdowns.

Vieselmeyer said there are technologies such as biometric scanning and data bracelets that can more accurately identify inmates before they are released, but the government usually doesn't implement them due to cost.

But he said the technology could be much cheaper than the cost of a massive manhunt if dangerous inmates escape, like the recent high-profile escape of two American prisoners from a correctional facility in New York state last month.

"As we saw in the New York situation, especially with the manpower, the cost factor was huge," Vieselmeyer said.

"If (the inmate) is out and he commits a crime while he's out, how do you gauge that cost if you had proper equipment to stop that release? It's one of those balancing things. Is the cost favourable if it stops another crime from being committed?"