In April, when the state Senate gave Department of Public Safety Director Nolan Espinda the thumbs-up to head the corrections system for another four years — rejecting the thumbs-down advice of a Senate committee — Espinda vowed to address a litany of leadership-related concerns.

Among the matters raised during hearings before the committee: incarceration of prisoners beyond their release dates. In March, DPS acknowledged that in 2018, nine inmates had been locked up beyond the date they were legally supposed to be released.

Since then, citing an ongoing investigation, the agency has declined to provide some basic information about the over-detainment cases — requested by the Honolulu Star-Advertiser and others. Nineteen months have passed since one of inmates was finally released. The glacial pace of the probe is unacceptable.

Whenever public safety is threatened as well as in any instance in which constitutional treatment of an inmate is in doubt, the corrections system’s leader has a duty to swiftly and candidly address the problem and propose remedy. Espinda needs to step up the pace of investigation and the level of public transparency.

Further, raising questions about whether the scope of the nine cases represents tip-of-the-iceberg trouble are researchers who worked with a joint program including DPS and University Hawaii that started in 2017 and abruptly ended this year.

Researchers told the Star-Advertiser that DPS data indicated about 10% of inmates have been over-detained in Hawaii’s jails and prisons in past years, though they couldn’t tell whether all of those inmates had indeed been over-detained or if the data were just riddled with errors.

Edward Suarez, who served as director of the DPS-UH Research and Evaluation in Public Safety program, has said that due to an apparent flaw in a DPS database, calculation for maximum release dates for thousands of past and present inmates was not reliable. The flaw, Suarez wrote in a July 18 commentary on these pages, could be fixed with available software programming for about $50,000.

DPS officials have said that the 10% estimate is wrong. But in response to a Star-Advertiser request for data verifying that assertion, a top official last week said it would cost more than $1 million in work hours to compile the information through review of some 125,000 inmate records. The agency’s response is ludicrous.

For starters, the Star-Advertiser requested a dataset for the years 2000 to 2018 — not a tally based on DPS review. The raw numbers should be accessible to the public. And if the database is indeed error-ridden, the agency should publicly own that and prioritize a cost-efficient fix.

Back in 2004, the state entered into a $1.2 million class-action settlement agreement to resolve hundreds of claims arising from failure to release inmates on time. It’s troubling that in the subsequent 15 years, the agency has yet to nail down a foolproof means for monitoring inmate detainment.

In the latest instance, upon the return of an Oahu Community Correctional Center inmate into custody on Monday, DPS had no real answers to questions about the man’s erroneous release on Saturday, saying the case is under investigation.

Espinda’s vow to lawmakers to better address public safety-related concerns is a tall order.

This year, in addition to detainment-related snags, the litany includes: moving forward in the aftermath of a riot at the Maui jail, and fatal shootings of an Oahu jail inmate and a homeless man. Long-standing concerns range from overcrowded and dilapidated facilities to an alleged culture of retaliation and intimidation within the department.

DPS’s leader is not responsible for all that is inherited, of course — but Espinda should rank this obvious detainment problem as meriting urgent attention.