Minnesota’s prison health care system lacks adequate oversight and outside accountability — factors that have contributed to inmate deaths and lapses in care, Legislative Auditor James Nobles said Thursday in a long-awaited report.

State examiners reviewed the mortality records of deceased inmates and concluded that deficiencies in care, in many cases, contributed to deaths. In what would be a major policy shift, auditors recommended that the Department of Corrections adopt a more transparent policy that includes outside reviews, similar to those used by the state Department of Human Services.

Nobles’ staff concluded that Minnesota inmates “have considerable access to health care,” but also said the Department of Corrections’ “compliance with professional standards is mixed, with room for improvement.”

A 2012 Star Tribune investigation found that at least nine prisoners had died in the previous 12 years after medical care was denied or delayed by corrections staff, and 21 more suffered serious or critical injury.

Corrections Commissioner Tom Roy declined to answer reporters’ questions Thursday morning but released a statement saying:

“The auditor’s report finds that Minnesota has the lowest rate of offender deaths in the entire country, which speaks volumes about the quality of our correctional health care.

“The report validates our efforts and gives us a foundation to build upon for the future,” the statement continued.

The audit, released Thursday morning at a legislative hearing, said that examination of inmate mortality reports revealed inadequate communication among staff members, mistakes in medication administration and insufficient documentation. It found that the mortality reviews have taken longer to complete than recommended by professional standards and that they were not shared with the medical staff whose performance was reviewed.

It also recommended improvements in care for inmates with chronic ailments and heightened attention to inmates with mental illness.