The federal agency that regulates nursing homes must take more aggressive steps to prevent and respond to violent crimes and other forms of abuse in senior care facilities, U.S. Sen. Amy Klobuchar said Tuesday.

In a letter to the U.S. Department of Health and Human Services, the Minnesota Democrat cited a five-day, Star Tribune special report published this month that detailed repeated failures by regulators to investigate incidents of criminal abuse in senior care homes across Minnesota.

The report found that hundreds of vulnerable residents at senior care centers are beaten, sexually assaulted or robbed each year. Yet the vast majority of these incidents are never investigated, and the perpetrators typically go unpunished. The series also highlighted how abuse victims and their families are often kept in the dark, for months or even years, as state investigations drag on indefinitely and facilities keep the incidents secret.

Klobuchar also asked U.S. Comptroller General Gene Dodaro, head of the Government Accountability Office, to review federal nursing home regulations and recommend changes to current practices at HHS and federal law that would better protect senior citizens from abuse. She suggested that new federal standards could reduce the long delays associated with many maltreatment investigations and require that families be notified within a set timetable after an incident of abuse.

"There are clearly major, major problems that are resulting in serious injuries, rip-offs and even deaths," Klobuchar said in an interview. "We need to look at everything from the timeliness of the [abuse] investigations, to the notification of family members, to our federal laws … and come up with some solutions."

Klobuchar's statement comes amid a wider call for reform at the State Capitol. Earlier this month, Gov. Mark Dayton also responded to the Star Tribune series, announcing that he would create a cabinet level task force to address shortfalls in the state's effort to protect elderly residents from abuse. Sen. Karin Housley, R-St. Mary's Point, chairwoman of the Senate Aging and Long-Term Care Policy Committee, said she is working on a package of reforms with input from elder advocacy groups.

Last year, the Minnesota Department of Health received more than 25,000 allegations of neglect, physical abuse, unexplained serious injuries, and thefts in state-licensed homes for seniors. While the agency reviews each of these allegations, only 3 percent were investigated on site by state inspectors, records show.

In the rare cases when the state did investigate, the investigations would often drag on for months, undermining the ability of local prosecutors to bring criminal charges. The long delays also frustrate victims and their families, and make it difficult for them to move on with their lives, the Star Tribune found.

"A recent report revealed troubling accounts of physical and sexual abuse of senior citizens in Minnesota nursing homes and assisted-living facilities," Klobuchar wrote in a letter to Eric Hargan, acting secretary of the U.S. Department of Health and Human Services (HHS). "Many of these incidents were either insufficiently investigated or not investigated at all."

In one incident from 2016, a 78-year-old woman with Alzheimer's disease was sexually assaulted in her bed by a male nurse's aide at an assisted-living facility in Pequot Lakes, Minn. Despite having an eyewitness, the facility waited nearly two hours to report the assault to police, and the victim's family was never notified by law enforcement officials or the state. In addition, the victim's nightgown and mattress pad were placed in the washing machine, destroying critical evidence.

"This is just one example of a problem affecting seniors across the country," Klobuchar said.

Klobuchar, a former prosecutor, also raised questions about whether federal and state regulators are ensuring that incidents of potential criminal abuse are reported to the police.

She pointed to a recent federal report, by the HHS inspector general's office, which found that more than one-quarter of serious cases of nursing home abuse are not reported to the police, despite state and federal laws requiring prompt reporting. Federal auditors reviewed a sample of 134 incidents of abuse in 33 states that were serious enough to send the nursing home resident to the emergency room. In 38 of the cases, auditors could find no evidence in hospital records that the abuse had been reported to law enforcement.

"Given the aging of the population, we need a major revamp of some of our laws around long-term care," Klobuchar said. "And one of the more important areas that we need to review and to make changes is to reduce the amount of fraud and abuse."