By Pat Anson, Editor

A gunman who fatally shot an Indiana doctor this week was upset because the physician refused to prescribe opioid pain medication to his wife, according to police.

Dr. Todd Graham was confronted Wednesday afternoon in the parking lot outside a South Bend medical center by 48-year Michael Jarvis. After a brief argument, Jarvis shot Graham twice in the head. Jarvis then drove to a friend’s house and killed himself, according to the South Bend Tribune.

An investigation later determined that Jarvis’ wife had an appointment with Graham Wednesday morning and the doctor declined to prescribe an opioid medication for her chronic pain.

“It was Dr. Graham’s opinion that chronic pain did not require prescription drugs,” St. Joseph County Prosecutor Ken Cotter said at a news conference Thursday. "He did what we ask our doctors to do. Don't over-prescribe opioids.”

Michael Jarvis was present during his wife's appointment and argued with Graham. Jarvis eventually left, but returned in the afternoon with a gun and confronted the doctor outside the medical center.

"Make no mistake, this was a person who made a choice to kill Dr. Graham. This is not a fallout from any opioid epidemic or any opioid problems. That probably leads us into an examination of what is happening with the opioid problem in our community, and frankly, in our whole nation," said Cotter.

Cotter said Jarvis had a “confrontation” with Graham before Wednesday, but did not go into details.

"This was a very targeted attack," said Commander Tim Corbett of Saint Joseph County Metro Homicide. "I am a firm believer -- and I think Ken feels the same way -- that if Jarvis would have got inside that building, although there wouldn't have been any specific target, it's like trapping an animal in a corner: they're going to come out fighting. I truly believe this could have escalated into a mass shooting. I do believe that."

Mrs. Jarvis was apparently unaware of her husband’s plans.

"It was clear that she didn't know what he was doing. She's suffering as well," Cotter said.

The 56-year old Graham was married and had three children. His obituary can be seen here. Graham's wife learned of her husband’s death through social media, according to the South Bend Tribune.

Several of Graham’s patients left messages about him on the Tribune’s website.

“He was a very caring person. I am lost of words my heart is breaking for his wife and family,” wrote one patient.

“Dr. Graham has been my Dr. for 3 years. After 3 accidents, and surgeries he has helped me tremendously. My condolences to his wife. He will be missed,” wrote another.

The Indiana shooting was the third in recent months involving a pain patient and a doctor.

In June, a gunman shot and wounded two people at a Las Vegas pain clinic before taking his own life.  The shooter, who suffered from chronic back pain, had been denied pain medication during an unscheduled appointment.

In April, a disgruntled pain patient in Great Falls, Montana burned down a doctor's home, held the doctor's wife at gunpoint and killed himself during a standoff with police.