The Arkansas State Police is investigating the death of another inmate.

Ronnie Martin, 35, was serving a 20-year sentence at the Cummins Unit after being convicted on drug charges out of Cleburne County.

The Arkansas Department of Correction (ADC) says Martin was pronounced dead on Tuesday night. He had been disciplined five times since June for alcohol or drug violations.

His death comes at a time that officials and lawmakers investigate the suspected drug overdoses of five inmates who died last month at a different Arkansas prison. ADC spokesman Solomon Graves says there’s no indication that Martin’s death is linked to the earlier deaths and that there was nothing conclusive showing drugs were involved.

What is known is that the deaths of four other inmates were caused by K2.

Back in February 55-year-old Phillip Hardy died in his cell at the East Arkansas Regional Unit at Brickeys.

A “Leafy substance that appeared to be K-2” was found in Hardy’s cell, according to a report from the Arkansas State Police.

Deangelo Merriweather, 23, was also serving time at in the maximum unit barracks of Brickeys when he died in May.

“Two suspected synthetic marijuana cigarettes were found in his cell,” the report stated.

Also in May, 53-year-old Henry Bunch was found dead in his cell at Cummins prison.

His cellmate told investigators that “Bunch had been smoking K2 prior to his death,” the report stated.

And 33-year-old Adam Bond died in Tucker Maximum Security a week before his parole hearing.

In his cell were “two rolled paper cigarettes that did not appear to have any contents. One of the cigarettes had been burned on one end as if it had been partially smoked.” Bond’s “…cause of death was synthetic cannabinoid intoxication,” the report stated.

It is still unknown how the K2 that killed each of these men got into the prisons.  Officials from the prison system says there have been a total of six inmate deaths this year linked to K2.