YOUNGSTOWN — Marco J. Cardenas, 34, of the Ohio State Penitentiary, pleaded guilty to possessing a deadly weapon while under detention last week and was sentenced to an additional 3 to 4 1/2 years in prison. Cardenas is serving a life prison sentence for killing Jack Manigault in Youngstown in 2011.

Manigault was the brother of Omarosa Manigault of Youngstown, who came to fame on “The Apprentice” television show.

Cardenas went on trial in September on possession of a deadly weapon with a notice of prior conviction, attempted murder with a criminal gang-activity specification and repeat-violent-offender specification, felonious assault with a criminal-gang-activity specification, notice of prior conviction and repeat-violent-offender specification, and possessing criminal tools.

Judge Anthony D’Apolito declared a mistrial, and the case was rescheduled to be heard Monday. But, Cardenas entered a plea Thursday and was sentenced.

The charges relate to allegations that on March 29, 2021, Cardenas made a makeshift knife while in the Ohio State Penitentiary in Youngstown and tried to kill another man. He also was accused of being a repeat violent offender.

Cardenas’ sentence was ordered to be served in addition to his sentence of 21 years to life after being convicted in 2012 in Mahoning County of aggravated murder, felonious assault and aggravated burglary in Manigault’s death.

In the Manigault case, police said Cardenas, then 22 and living on Plymouth Street, forced his way into his former girlfriend’s home on East Avondale Avenue while she was sleeping and shot and killed her boyfriend, Jack Manigault,

Omarosa Manigault, 40, grew up in Youngstown and graduated from The Rayen School.