Updated

A man suspected of shooting dead George H.W. Bush's former doctor apparently tried to sell guns online days after carrying out the murder, according to reports.

Joseph James Pappas, 62, on Wednesday was named the suspect in the shooting death of prominent Houston cardiologist Dr. Mark Hausknecht, who was killed while biking to work on July 20. Pappas may have carried out the murder because of a 20-year grudge stemming from his mother’s death in the 1990s.

84949d9d-Pappas 720

Joseph James Pappas, 62, was charged in the murder of Dr. Mark Hausknecht. Police are searching for the suspect. (Houston Police)

Five days after the killing, a stash of weapons — including two tactical vests, a .38-caliber revolver and ammunition — was listed for sale on a popular firearms website, the Houston Chronicle reported. The seller’s number was traced back to Pappas’ real estate company. It’s unclear if any of the weapons was used to kill Hausknecht.

Mark Hausknecht

Hausknecht was a well-known doctor who once treated former President George H.W. Bush. (AP)

The cache amounted to thousands of dollars, the report stated.

SUSPECT IDENTIFIED IN MURDER OF GEORGE H.W. BUSH'S FORMER DOCTOR

Houston police combed through surveillance and tips for nearly two weeks before naming Pappas the suspect.

"We need to find this guy," Houston Police Chief Art Acevedo said of Pappas, who he described as armed, dangerous and possibly suicidal. "If he's committed suicide, we need the body. If he's alive, we need to find him."

hausknecht suspect

Authorities released a sketch of the gunman and surveillance video days after the shooting. (Houston Police)

Along with being a real estate agent, Pappas previously served in the Harris County Constable’s Office for about 30 years. His mother died in surgery under Hausknecht’s care more than two decades ago, possibly causing Pappas to hold a 20-year grudge against the doctor.

SURVEILLANCE IMAGES SHOW GUNMAN BEHIND GEORGE H.W. BUSH'S FORMER DOCTOR MOMENTS BEFORE MURDER

Pappas has been charged with murdering Hausknecht, though no one has seen him for at least 36 hours. He reportedly also transferred his home’s deed a day before shooting and killing the cardiologist.

President Bush was treated by Hausknecht in 2000 for an irregular heartbeat after he complained about lightheadedness. Bush paid tributed to him as a "fantastic cardiologist and a good man".