PORTLAND, Ore. (Portland Tribune) — A man who built an impromptu swimming pool during last month’s historic heat wave was killed shortly thereafter in self-defense during a drug dispute, authorities say.

A Grand Jury convened by the Multnomah County District Attorney’s Office issued a “no true bill” on July 22 — declining to bring a first-degree manslaughter charge in the death of Tyson Leigh Morlock.

Originally hailing from Washington state, the 27-year-old had been living in homeless camps at Delta Park and then underneath the 99E overpass at Southeast 6th Avenue and Division Street after hitching a ride to Portland from Seattle with a friend, Mark Corwin, who also lived nearby in his car, records say.

As the mercury rose to record-shattering heights, Morlock cobbled together an above ground watering hole, garnering mentions from The Guardian newspaper and local media on June 30.

But as night fell the campers became embroiled in an argument over several missing items, including a vanished quarter pound of meth, a prosecutor’s report obtained by the Tribune says.

Per the report Corwin pointed the finger at Morlock, who flew into a rage, grabbing metal tent poles and charging Corwin. The 26-year-old tumbled down the embankment and fled, according to the report.

“Corwin continued to run away and (Morlock) chased after him, threatening to kill him, brandishing the metal tent poles,” deputy district attorney Amber Kinney wrote. “Corwin said he was terrified, (while Morlock) was erratic and unpredictable.”

After losing ground during a two-block chase, Corwin realized he could not outrun Morlock, the report says; he whipped around and pulled a knife as Morlock charged with the poles raised. Corwin told investigators he stabbed Morlock once in the left torso, took off his shirt and applied it to the wound, then dialed 911.

It was about 3 a.m. on July 1.

“(Corwin told 911) he stabbed the victim, but had no choice,” the report says. “Corwin sounded distraught.”

Morlock was rushed to OHSU, where he died.

Corwin cooperated with homicide detectives, and several other campers corroborated his story, the report says. Morlock’s mother Randi Shelton, however, is dismayed with the grand jury decision and is considering a lawsuit.