They're out of sight, but must not be out of mind. Hawai'i's overflow inmate population, housed at private prisons on the Mainland, remain our responsibility. And making sure they are treated humanely while serving their time must be our concern.

That's why state officials are right to demand an investigation into the sudden opening of cell doors in the predawn hours of July 17 at Tallahatchie County Correctional Facility that resulted in a riot. More than 700 Hawai'i inmates have been housed since last year at the Mississippi prison, owned by Corrections Corp. of America.

Two inmates were injured in the fight. Kane'ohe resident Sandra Cooper, the mother of one inmate, has her doubts that an internal probe will be enough to bring out the truth about how the cell doors opened. She called on the FBI to do a thorough inquiry, and that indeed would be the ideal way to proceed here. There's precedent for the FBI to take jurisdiction in a case where inmates are brought across state lines.

At the very least, an independent authority should drive the investigation, rather than the prison's private owners. And state officials here must continue to ride herd to see that the investigation proceeds to a satisfactory conclusion.

In a separate prison issue, it's a relief to see that the state has decided to pull the plug on its contract with the troubled Brush Correctional Facility, a northeastern Colorado prison housing 80 women inmates from Hawai'i.

Because of ongoing investigations into alleged sexual misconduct between staff and prisoners, it's imperative that the move be made as soon as possible, while allowing for careful scrutiny of the prisoners' next destination. The end-of-September target date for the move seems reasonable, assuming that the state maintain its careful monitoring of Brush in the meantime.

These painful episodes clearly illustrate that housing inmates on the Mainland is merely a short-term response to our critical prison shortage here, and creates its own additional problems.

Hawai'i must continue to: work toward expanded prison capacity in the Islands, where we can retain better control of conditions; strengthen the probation system to keep some first-time offenders out of prison; and work on preventive strategies aimed at stemming the tide in drug abuse, which fuels so much of the state's crime problem.

Sending inmates to the Mainland is just a stopgap solution.