ALLENTOWN, Pa. -

An Allentown man has pleaded guilty, but mentally ill, in the murder of his mother.

Rafael Tirado pleaded guilty Thursday to charges including third degree murder and tampering with evidence.

Officials say, in May 2012, Tirado stabbed his mother Gloria Santiago to death in her home in the 1600 block of Tilghman Street.

Tirado's family says he suffers from schizophrenia.

He will spend 25 to 50 years behind bars.