BUTLER TWP — Two men are in the Butler County Prison on charges stemming from the ongoing investigation into five suspected drug overdose deaths in the county this month.

Eugene J. Smith 47, of Butler Township and Michael D. Burrows, 30, of Wilmerding, Allegheny County, were arrested Thursday at Smith’s apartment at Old Plank Estates.

Both defendants are charged with felony and misdemeanor drug possession and conspiracy. They were placed in the county prison overnight to await arraignment this morning.

But more serious charges could be added as the investigation moves forward, said Butler County Assistant District Attorney Ben Simon.

Local police departments and the Butler County Drug Task Force launched the joint investigation following the deaths — two in Butler Township and one each in Adams and Slippery Rock townships and in Butler.

While authorities suspect the victims died of drug overdoses, possibly from heroin or a heroin mixture, the cause of death in each case is pending results of toxicology tests.

Those results aren’t expected for at least two weeks, investigators said.

The arrests of Smith and Burrows followed evidence gathered by Adams Township police investigation into the death of Elizabeth H. Arblaster, 24, of Cherry Township.

Police said Arblaster was found about 10:10 a.m. Saturday in the bedroom of a home on Stoup Road in Adams Township that the woman had been visiting. A family member discovered her unresponsive.

Officers later turned up more than a dozen empty stamp bags of suspected heroin and at least six more full bags in the bedroom. Officers also found syringes in the bedroom.

A number of those bags, which were black and white with a gorilla face, were marked with the name “The King.”

Butler County Detective Tim Fennell, who heads the county’s drug task force, noted in court papers that similar bags were found at some of the scenes of the other overdose cases.

Investigators suspect Arblaster on Sept. 2 purchased heroin from Smith at his home. The investigation eventually led police to obtain the search warrant Thursday.

Authorities declined to immediately say what evidence they seized from Smith or the apartment.

But Burrows was at the apartment, and he, too, was arrested.

“He had a large amount of cash in his pocket and also drugs on or around his person,” Simon said. He declined further comment about Thursday’s arrests or the continuing investigation.