Area man pleads guilty in bloody slaying case

Mario Alejandro Perez Santos was stabbed with a knife and beaten with an aluminum bat last year.

By PAULA REED WARD
TribLive

A West Mifflin man pleaded guilty Monday to voluntary manslaughter in the stabbing and beating death of someone staying at his home last year.

Andy Steven Nimajuan Sitan, 21, will be sentenced by Allegheny County Common Pleas Judge Simquita Bridges on Jan. 5.

According to Assistant District Attorney Nicholas Creany, police were called to a trailer home in the 1100 block of Thompson Run Road around 10:45 p.m. on Aug. 16, 2025, after neighbors reported hearing screaming.

When officers arrived, they found Nimajuan Sitan on the floor covered in blood, Creany said. Underneath him, the prosecutor added, they found a bloody knife.

Nearby, they found the victim, Mario Alejandro Perez Santos, 35, who had been staying with him. An aluminum bat was nearby, according to Creany.

Nimajuan Sitan told police, “‘He tried to kill me,’” Creany said.

According to the investigation, Nimajuan Sitan and Perez Santos had been working outside that day, and the two men were drinking.

“Sitan told (the victim) he didn’t want to drink with him anymore,” Creany recounted, which he said made Perez Santos angry.

Perez Santos attacked Nimajuan Sitan with a knife, the prosecutor said, and said he would kill him.

“Sitan was afraid for his life,” Creany said.

Nimajuan Sitan grabbed the knife with both hands and wrestled Perez Santos to the floor.

The defendant told police that after Perez Santos attacked him, he grabbed an aluminum baseball bat for protection and struck Perez Santos multiple times.

Nimajuan Sitan was taken to Jefferson Hospital with multiple lacerations to his hands. Testing there showed his blood alcohol concentration was 0.184% — more than twice the legal limit to drive.

The scene inside the house, Creany said, was gruesome, with a pool of blood on the counter and more blood on the ceiling and hallway.

Perez Santos, the medical examiner’s office said, died from blunt force trauma to his head, neck and torso.

He also had stab wounds, including one to his head, three to his neck and 13 to his torso, Creany said.