The Minnesota Security Hospital in St. Peter violated state law and its own policies last fall by strapping a patient with developmental disabilities to a restraint chair and then pulling a hood over the patient’s face, even when the patient posed no imminent threat, according to a state investigative report released Tuesday.

The state’s largest psychiatric hospital, which treats about 360 of Minnesota’s most psychiatrically complex and dangerous patients, has significantly reduced incidents of restraint and seclusion over the past decade. Even so, the recent incident highlights how the facility is still struggling to adhere to state regulations designed to phase out the practice except in extreme circumstances. The hospital has been cited 11 times since December 2016 for violating state licensing rules governing the use of restraints, state records show.

State investigators found that staff at the Security Hospital last September placed a patient with autism spectrum disorder and a history of aggression in a restraint chair for more than an hour, and pulled the patient’s sweatshirt over his head to prevent spitting. These actions “were not therapeutic” and violated state law that restraint and seclusion should be used only as an emergency measure to prevent imminent risk of harm, state investigators found. The hospital was fined $1,000 for the violation.

The patient, unidentified in the report, had refused medications and was making verbal threats, but there were no other patients or staff members near the patient at the time, investigators found.

“There was a preponderance of the evidence that staff persons’ actions of manually and mechanically restraining the [patient] when it was not warranted … were not therapeutic, escalated the [patient’s] behaviors, could reasonably be expected to produce physical pain, injury, or emotional distress, and represented a failure to provide the [patient] with reasonable and necessary care,” concluded the Minnesota Department of Human Services (DHS), which oversees the hospital, in the 17-page investigative report.

In a written statement, Human Services Commissioner Jodi Harpstead said the agency is “troubled by the incident” and will develop a comprehensive plan and reinforce staff training on how to de-escalate incidents and evaluate risk before using restraints. She noted that restraints should be used as “a last resort” to protect a patient and others from harm.

The use of seclusion and mechanical restraints in the treatment of people with developmental disabilities has been widely condemned as inhumane, dangerous and largely ineffective. Disability advocates have long encouraged the state to use less-restrictive techniques, and the Security Hospital trains staff on how to redirect and calm agitated patients rather than resorting to physical restraints and seclusion.

In 2011, as part of a federal class action settlement, the DHS agreed to “immediately and permanently discontinue the use of mechanical restraint” at a now-shuttered state facility in Cambridge, where adults with developmental disabilities were routinely restrained with leg hobbles and handcuffs. The agency also agreed to extend the terms of the settlement to all state-operated locations serving people with developmental disabilities. The state made an exception for the use of restraints in cases when a person posed “an imminent risk of harm to self or others.”

These changes coincided with a broader effort to improve the therapeutic environment at the Security Hospital and to root out the facility’s punitive culture. The amount of time patients spend in restraints and seclusion has declined by nearly 45% over the past two years, from a total of 94 hours per month in 2017 to 52 hours per month last year. Safety has also improved: Injuries resulting from patient aggression have fallen by more than 50% since 2015, according to DHS data.

Yet state records indicate that mechanical restraints are still very much in use at the Security Hospital. In February of last year, for instance, a patient was calmly rocking back and forth, when staff approached from behind and forcefully moved the patient to a restraint chair and placed a spit hood over the patient’s head. The patient was kept in the chair, yelling periodically, for 2 hours and 17 minutes. The state found the staff members’ actions were not warranted because the patient did not pose a risk of imminent harm, according to a state investigation issued last July.

“They should not be using mechanical restraints on people with intellectual and developmental disabilities. Period. End of story,” said Roberta Opheim, state ombudsman for mental health and developmental disabilities. “It’s traumatizing and can result in injuries to both the staff and to the clients.”

In the most recent incident, investigators found video footage showing that the patient had become agitated and was repeatedly punching a plexiglass window. However, the video also shows that staff members were able to engage the patient, who was on an upper landing and away from other patients, investigators found. Still, the patient was escorted to a restraint chair at 4:05 p.m. and was not released until 5:20 p.m., the report said.

State investigators also found that staff members did not accurately describe the incident in internal documents.