James McVay admitted to Madison, Wisconsin TV stations in July that he killed a Sioux Falls woman on his way to kill President Barack Obama.
Wednesday he admitted his crime to a judge.
James McVay pleaded guilty but mentally ill late Wednesday afternoon.
But, Judge Peter Lieberman says he won't accept the plea until he holds a psychiatric hearing in court.
"The court will find at a different hearing whether that plea will be accepted or not. It doesn't have any impact as far as the options available to a jury as far as sentencing options in a Class A Felony," Minnehaha County State's Attorney Aaron McGowan said.
Forty-one-year-old James McVay walked away from a transitional program at the South Dakota State Penitentiary July 1.
McVay says he killed 75-year-old Maybelle Schein in her Westside Sioux Falls home July 2, stole her car and headed east.
McVay was caught later that day near Madison, Wisconsin.
Its there he told authorities, and Madison TV stations, he was on a cross-country killing spree to assassinate the president.
McVay still faces the death penalty if the guilty but mentally ill plea is accepted by the judge. Minnehaha County State's Attorney Aaron McGowan says the crime was so serious that capital punishment is still on the table.
"Based on the facts and circumstances surrounding this case we need to put this in the hands of a Minnehaha County jury to make that determination as far as death or life in prison," McGowan said.
So, even though this confessed killer has admitted to the crime he could still face death himself.
The psychiatric hearing has not been scheduled yet.
This is the third South Dakota prison inmate to face the death penalty in Minnehaha County this year.