Spending 58 years behind bars has not only made Howard Christensen the nation's longest-serving inmate - it's made the slightly demented killer more cantankerous and disagreeable than ever.

He's harassed visitors, refused to change clothes or bathe and has been so unpleasant officials feared other inmates would attack him.Doctors gave him electric shock treatments and even considered giving him a frontal lobotomy to make him more docile.

Now prison officials have had enough. They want to put the 75-year-old inmate in a nursing home - but they are not sure they can find any takers.

"The world has changed a lot since 1937," said Rich Wiese, spokesman for the South Dakota State Penitentiary. "He's a difficult person."

Christensen has spent most of the past six decades in the prison and in hospital psychiatric wards.

He is now in a cell in the wing for mentally disturbed inmates, where his care costs taxpayers tens of thousands of dollars a year.

Medicare could pay the bills if he lived outside prison, but since Christensen is notorious for his behavior, it could be hard to find a nursing home for him, Wiese said.

Even if a nursing home is found, officials would have to determine that he is not a threat to society and Gov. Bill Janklow would have to reduce his life term to time served.

A prison geriatric ward would be another alternative, but South Dakota lawmakers have been reluctant to create such a facility.

The case shows that South Dakota, like other states, is ill-equipped to deal with aging prison populations, said Democratic state Rep. Pat Haley, a former prison guard who has interviewed Christensen for a book.

Christensen and another 17-year-old hitchhiker, Norman Westberg, shot and bludgeoned 28-year-old schoolteacher Ada Carey in a robbery.

The teacher's murder, which prompted the state Legislature to reinstate the death penalty in 1939, remains one of the most notorious in South Dakota history. Westberg hanged himself in 1943.