Pascasio Pacheco was accused of killing his aunt and uncle, Marisol Hernandez and Bulmaro Arellano, and their two children. Police say Pacheco shot and killed the couple, then set fire to their home on Highway 121 in Murray. The two children died of smoke inhalation.
When Pacheco plead not guilty in January of 2016, prosecutors indicated they would seek the death penalty in the case.
Thursday's guilty plea to four counts of murder, along with burglary, arson, tampering with physical evidence and assault, means Pacheco will not have a jury trial but will serve a sentence of life without parole.
Formal sentencing is set for February 18 in Calloway Circuit Court.
