Earlier today, the owner of a Boston barber shop, where Carpio told police he worked on the day Allen was killed, appeared on the witness stand.

Doyen Dunkley, of A-1 Barber Shop, denied knowing or ever seeing Carpio, now on trial for murdering Allen and stabbing an elderly woman hours before.

Later in the proceedings, Providence police Sgt. Robert Boehm, who works in the department's weapons unit, used Allen's holster -- known as a pancake holster -- to show the jury how one would remove the gun. In a detailed demonstration, Boehm used Allen's actual gun, its evidence tag hanging off.

Trooper testifies he punched Carpio in the face

Journal photo / Kathy Borchers
Christopher Zarrella, a state police detective who helped arrest Esteban Carpio, points to Carpio during Carpio's murder trial today in Superior Court, Providence.

State Police Detective Chistopher Zarrella testified today that in arresting Carpio last year he punched Carpio three times in the face with his closed fist.

Zarrella, the first witness to testify today said he hit Carpio on Washington Street a few blocks from police headquarters.

"I struck him because he was trying to strike me. And I thought he had a weapon,'' Zarrella testified.

He added during further questioning that Carpio was swinging at him and that he believed that his life was in danger.

Until today's testimony, the public never knew who injured Carpio the night of the arrest. According to today's testimony, Zarrella broke bones in Carpio's face.

Carpio last year wore a protective face shield at his arraignment, which corrections officials said was to prevent him from spitting at officers.

A spokeswoman for the state Department of Corrections called the use of the mask a rare security measure. The spokeswoman did not mention Carpio's injuries.

-- Staff writer Gregory Smith