SOLEDAD (CBS SF) — A reputed gang member who was convicted of conspiring to murder a fellow gang member in San Leandro in 2011 has been arrested in connection with the fatal stabbing of a fellow inmate at the Salinas Valley State Prison in Soledad on Tuesday, prison officials said.

Jacob Castro, 38, has been named as the suspect in the death in the death of 26-year-old George Argueta, who was convicted of second-degree robbery in Santa Cruz County in 2012, according to state Department of Corrections officials.

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Shortly after 11 a.m. Tuesday staff members at the Salinas Valley State Prison who were performing security checks noticed Argueta lying on the floor in his cell, prison officials said.

An alarm was sounded and responding staff immediately removed Argueta from the cell and began administering life-saving measures.

A suspect, later identified as Castro, was removed from the cell without incident and an inmate-manufactured weapon was recovered at the scene, according to prison officials.

Argueta suffered multiple stab wounds to his upper chest and was pronounced dead at 11:26 a.m., according to authorities.

Castro is being held in the prison’s administrative investigation unit as the stabbing is investigated, prison officials said.

The Monterey County District Attorney’s Office is assisting in the investigation and the Office of the Inspector General was notified, according to the Department of Corrections.

Argueta was serving a 12-year sentence and was scheduled to be paroled in 2024, prison officials said.

Castro was sentenced to 25 years to life in state prison in 2013 for conspiring to murder a fellow gang member who had identified two suspects in a fatal shooting at the Viper Lounge in Hayward in 2008, Alameda County prosecutors said.

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Castro directed three colleagues to kill their fellow gang member and his family at their home in San Leandro in July 2011, prosecutor John Brouhard said at Castro’s trial in 2013.

Castro was upset at the man for cooperating with authorities in the investigation of the Aug. 30, 2008, shooting death of 24-year-old Nathan Tuitasi at the Viper Lounge, located at 29308 Mission Blvd. in Hayward, according to Brouhard said.

However, Hayward police learned of the plot to kill the intended victim, conducted an intensive undercover operation that included making surveillance videos and were able to stop Castro and his colleagues before they could carry out their plan, Brouhard said.

On July 8, 2011, police arrested Castro in Castro Valley and co-defendants Johnny Brown, Lorenzo Farfan and Ruby Farfan in San Jose, according to Brouhard.

In a sad twist in the case, the man the four defendants were plotting to kill later died of cancer before Castro’s 2013 trial, Brouhard

Brown, Lorenzo Farfan and Ruby Farfan all pleaded no contest to attempted murder, Brouhard said.

Witnesses to the fatal shooting at the Viper Lounge said it resulted from a dispute between two groups of people, Hayward police said.

Brouhard said the gang colleague Castro and the other defendants wanted to kill identified two men who were involved in killing Tuitasi, as the colleague was at the bar at the time of the shooting. Those two men later pleaded no contest to voluntary manslaughter for Tuitasi’s death, Brouhard said.

Department of Corrections officials said Castro was convicted of assault with a deadly weapon for an attack on a fellow inmate in January 2015 and was sentenced to an additional 8 years in prison.

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