Grapevine police and the Northeast Tarrant County Drug Task Force are investigating two recent deaths that may be linked to a batch of heroin.

Pablo Brena, 34, of Argyle and Cassidy Seward, 18, of Grapevine both died in Grapevine within the past week. The official cause of death is pending toxicology reports, but officials believe both are linked to heroin use.

"We strongly believe at this point that it's going to be heroin," said Grapevine police Sgt. Robert Eberling.

Officers responded to the 800 block of E. Walnut St. in Grapevine shortly after midnight Sunday for a suspected overdose to find Brena. He was rushed to Baylor Medical Center of Grapevine where he was pronounced dead at 1 a.m.

Brena has an extensive criminal background with convictions for possession of a controlled substance, intent to manufacture and deliver controlled substances, possession of marijuana, driving while intoxicated and assault.

Seward was found at 4:38 p.m. Tuesday in the 400 block of Holly Street and pronounced dead from a suspected overdose.

Grapevine police say teenager narcotic deaths are not completely uncommon, but they emphasize the presence of resource officers in schools to warn of the dangers of drug use.

Isolating a source of the possibly deadly heroin could prove to be difficult for Grapevine police and the drug task force.

"It's not like your typical urban city where you have a section of town that's heavily known for drug use or drug dealing," said Eberling. "Grapevine is not that type of city."