Five people were arrested during a series of drug raids Tuesday that resulted from an investigation into a rash of sometimes deadly heroin overdoses.

Portland Police Sergeant Brian Schmautz said officers raided three locations in Southeast Portland Tuesday morning.

the investigation started when police found 28-year-old Kevin Caldwell Stoll dead in Northwest Portland last March. In that case, evidence led drug detectives to arrest 49-year-old Richard Williams. 

Schmautz said police eventually dug up evidence of the drug ring that was unloading about two pounds of heroin on Portland streets every month.

There were three drug overdose deaths over the past weekend, police said. Since June, Portland Police have responded to more than 115 heroin-related calls.

"There's an increase in the purity level of heroin in the Portland area and that's the biggest thing that contributes to these overdoses,” says Portland Police Captain Mark Kruger.

That purity level can have deadly consequences for users.

More: Man dies after using heroin just once

Between Friday and Monday, police responded to three fatal heroin overdoses. One was a transient found dead inside a tent in Washington Park. A number of syringes surrounded the man’s body.

On Tuesday officers found $17,000 in cash, an ounce of heroin and what they called a repackaging room where workers would put the heroin in balloons for sale.

Police arrested 21-year-old Casiano Huerte-Diego, 18-year-old Edgar Zavala-Rodriguez, 19-year-old Martin Camacho-Ramirez, 23-year-old Jose Gilberto Gracian and 23-year-old Kevin Omar

"The pipeline in the western United States (for heroin) is up I-5 from Mexico,” says Captain Kruger, “and so we're right in the middle of that pipeline.”

Miguel Tellez of Cascadia Behavioral Health knows the dangers of heroin. A drug counselor for more than a decade, Tellez says a heroin high is difficult for users to top

“You don't know where you're at or what you're doing,” says Tellez. “You're just having physical pleasures, euphoric feelings.”

Tellez says it’s almost impossible for users to quit once they’re hooked, despite terrible side effects: “You get some terrible stuff, shakes, tremors, hallucinations, and pain,” says Tellez.

The pure form of heroin being peddled in Portland means users are getting the equivalent of a higher dose, one that can be deadly.

While police try to track down the dealers, health officials are trying to get the word out in the drug using community, hoping it curbs the problem.

KGW Reporter Mike Benner contributed to this story.