A Baton Rouge man pleaded guilty Monday to manslaughter in a 2013 beating death and agreed to testify truthfully against his father when the elder man stands trial next month on a second-degree murder charge in the killing.

Shedrick D. Lobrano, 27, now faces a sentence of up to 40 years in prison in the death of Lionell Trumble, 60.

His father, Shedrick L. Lobrano, 53, would be sentenced to life in prison if convicted of second-degree murder.

State District Judge Mike Erwin, who indicated Monday that the younger Lobrano gave East Baton Rouge Parish prosecutors a recorded statement, warned that if he testifies differently at his father’s Dec. 14 trial, he won’t receive the sentence agreed to by his attorney and prosecutors.

Allen Myles, who represents the younger Lobrano, and prosecutor Melanie Fields declined to discuss the negotiated sentence after court. He will be sentenced after his father’s trial.

“We appreciate the fact that he was truthful today. We expect him to be truthful at his dad’s trial,” Fields said to Erwin, who will preside over the elder Lobrano’s jury trial.

The elder Lobrano’s attorney, Steven Young, declined comment when reached by phone.

Fields told the judge that Trumble was severely beaten when he intervened in a Jan. 5, 2013, fight between his sister and her ex-boyfriend — the elder Lobrano — on Ozark Street.

The younger Lobrano was passing by with friends and decided to join the fight, the prosecutor said. Both Lobranos punched and kicked Trumble while he was on the ground, she said, and the elder Lobrano continued to attack Trumble even after the younger Lobrano retreated and drove away with his friends.

Trumble was in a coma until he died March 12, 2013.

The Lobranos initially were booked on one count each of attempted second-degree murder, but the charges were upgraded to second-degree murder after Trumble died. The younger Lobrano’s charge was reduced to manslaughter last year.

A witness told police the younger Lobrano hit Trumble over the head with a wooden board, knocked him down and continued to hit him and stomp on him, according to an arrest warrant for the younger man.

Myles said after court that the younger Lobrano is a fine young man who “went to his dad’s defense.”

“I think he did what any young man would have done,” he added, noting that testifying against his father won’t be easy.

East Baton Rouge Parish District Attorney Hillar Moore III said the younger Lobrano was in college at the time of his arrest and had no prior arrests or convictions.

The younger Lobrano has been in jail for nearly two years, Moore said, but was expected to be released later Monday on a $1,000 post-conviction bond set by Erwin.