A convicted prisoner kills another in one of the few death row inmates at San Quentin Prison

SACRAMENTO, California – A convicted prisoner has killed another Friday, the first murder of a death row in California for more than 20 years, officials said.

Jonathan Fajardo, 30, was stabbed in the chest and neck with a weapon made by an inmate. The attack took place in the playground of the cell that houses most of the convicts at San Quentin State Prison, said penitentiary department spokeswoman Terry Thornton. Luis Rodriguez, 34, is considered the suspect, she said.

The investigators were trying to determine a motive and how the suspect was getting or was able to make the weapon, Thornton said.

These killings are common in California prisons but rare on death row, where the last was in 1997.

"It's very unusual," said Amy Smith, an associate professor at San Francisco State University, who studies capital punishment and the psychological impact of death row. "This is not supposed to happen, of course."

There is high security on death row, with each inmate being housed separately. Most are allowed to gather in small groups in the exercise yard where Fajardo was killed, Thornton said.

Smith stated that statistically, prisoners serving a life sentence and "rank-and-file" individuals generally have the lowest levels of violence in prison, even though it would appear that they could do something because they have the worst very very little violence in prison. "

The state prison of San Quentin is the oldest prison in California. It opened in 1852 and houses 4,398 inmates, according to reports from the CBS SF Bay Area.

Fajardo was admitted from Los Angeles County in May 2011. He was awaiting the execution of two counts of murder in the county for what was considered a hate crime. He also received seven life sentences.

Fajardo was identified as a member of a Latino gang that killed a 14-year-old black girl in a racially motivated shootout. Two weeks later, he had also been sentenced for the death with the knife. According to one prosecutor, he was killed because other members of the gang thought he might cooperate with the police.

Rodriguez was admitted from Los Angeles County in August 2008. He is awaiting execution for two counts of murder. According to local media reports, Rodriguez would be a member of another Latin American gang found guilty of murdering two men belonging to a rival gang. He was already suspected of another murder that would have resulted in a life sentence.

No one has been executed in California since 2006, although voters in 2016 have adopted an initiative to speed up the death penalty. Many more death row inmates on death row have died of natural causes or suicides than those executed since California reinstated the death penalty in 1978.