A criminology expert is praising the public safety minister's decision to order an investigation into how a prisoner was mistakenly released from the Saint John Regional Correctional Centre.

Public Safety Minister Robert Trevors announced the review into how Ronald McCutcheon, 20, who has since been charged with armed robbery in connection with this month's fatal home invasion on Saint John's lower west side, was released from jail.

Public Safety Minister Robert Trevors ordered a review into how an inmate was mistakenly released from a provincial jail. (CBC)

McCutcheon was sentenced to nine months in jail on 11 unrelated charges, including fraudulent use of a credit card, mischief, and resisting a constable, in September.

But he ended up serving little more than a month and a half before he was released from the Saint John jail.

Mary Ann Campbell, a criminology professor at the University of New Brunswick in Saint John, said the minister’s order is an important first step to figure out how the mistake happened and to ensure that it doesn't happen again.

“It sounds like the plan to review all the cases and fully assess to see whether this is a systemic problem or is it just a significant but single incident is an appropriate way to go,” she said.

The department has reviewed all records related to the inmate in question and all other offenders at the Saint John Regional Correctional Centre have been reviewed and confirmed as accurate.

A similar review is now underway at all provincial correctional facilities, Trevors announced last week.

Correctional managers are also working to ensure quality assurance practices will prevent similar incidents.

Liberal MLA Rick Doucet, the opposition's public safety critic, is asking how long the provincial government knew about the release before it was made public on Friday afternoon.

“This is a very unfortunate situation, one that we sincerely hope will never happen again,” Doucet said in a statement.

“However, it is important to find out when the minister knew about this. Did he try to keep this from the public? These are questions that demand a response from the minister.”