CHICAGO:-  Texas police were on the hunt Thursday for a former cop suspected of shooting dead an eminent doctor who once treated ex-US President George H.W. Bush, because of a 20-year grudge. Mark Hausknecht was killed two weeks ago while riding his bicycle to work. The 65-year-old cardiologist at Houston’s Methodist Hospital treated the former president in 2000. Police were searching for a 62-year-old ex-law enforcement officer whose mother died on Hausknecht’s operating table more than 20 years ago.–AFP

Houston Police Chief Art Acevedo told a news conference Wednesday that that was the motive investigators believe drove Joseph James Pappas to allegedly murder the doctor in broad daylight.

“The Houston Methodist family is still in shock about the senseless killing of one of our longtime physicians,” the hospital’s chief Marc Boom said in a statement.

“We are relieved that the Houston Police Department has identified the suspect,” he said.

Pappas had been in law enforcement from 1983 until he ended his service as a reserve officer in 2013, according to NBC News.

He was considered armed and dangerous, and authorities believed he could also be suicidal.

“The suspect had not been heard from by people that know him for over 24 hours and there is a text that he sent someone that said he was going to kill himself,” the police chief said.

Based on surveillance images, police believe Pappas was on a bicycle just behind Hausknecht on the morning of July 20 as he rode to work. The former cop then went past the doctor, turned and fired two shots, police said.

“There was a lot of planning that went into this. There was a lot of planning and, sadly, some skill,” Acevedo said.

Police on Wednesday issued an arrest warrant for Pappas and charged him with murder. They said he may be armed with multiple weapons.

Hausknecht’s memorial service was held Saturday.

At the time of the doctor’s death, former President Bush called him “a fantastic cardiologist and a good man.”

“I will always be grateful for his exceptional, compassionate care. His family is in our prayers,” the 41st US president said in a statement quoted by US media.