Blanchard Glaudin, 31, pleaded guilty to second-degree murder for the 2020 stabbing death of Sandra Wilson, a security guard at Finkelstein Memorial library in Spring Valley on Tuesday.

"Miss Wilson was a mother. Was well regarded and loved by the children at Finkelstein. It was a senseless act of violence," said Rockland District Attorney Thomas Walsh.

He explained why it took so long.

"There was a problem, the determination that the defendant was not competent to stand trial which led to much of the delay. He was found competent by the judge at the time of the plea so we we're prepared to proceed and go forward," he said.

In February 2020, Glaudin killed Wilson after she told him to lower the volume of music in his headphones.

District Attorney Walsh says they were seeking a sentence of 25 years to life but the judge's agreement is 20 years to life.

Glaudin's sentencing is expected to happen in February.

Wilson's family had earlier settled a lawsuit with the library saying Wilson had been harassed by Glaudin, but the library took no action.