A man suspected of killing George H W Bush's former doctor killed himself during a confrontation with authorities, police say. 

Mark Hausknecht, a 65-year-old cardiologist, was shot dead in broad daylight two weeks ago while riding his bicycle to work. 

Main suspect Joseph James Pappas, 62, shot himself after being confronted by police in Houston on Friday morning. 

He was wearing body armour and took his own life when a second police unit arrived. 

Image: Houston Police released this CCTV image of the shooting suspect

Authorities had announced Pappas was a suspect in the 20 July death of Dr Hausknecht, who was shot three times while cycling to Houston Methodist Hospital. 


Pappas is thought to have held a grudge against Dr Hausknecht after his mother died under his care more than 20 years ago. 

Image: Dr Hausknecht was captured on CCTV before his death

Police were called to the scene, around three and a half miles from Pappas' home, after a city worker reported seeing him in the area. 

Authorities had previously described Pappas as armed, dangerous and suicidal. 

According to his former friend, Pappas is believed to have had a "hit list" and was potentially on the hunt for his next victim. 

Image: Houston Police highlighted the suspect in CCTV still from the day of the killing

Dr Hausknecht was "number one on the list", the friend told Houston's KHOU-TV. 

Police said the gunshots Pappas allegedly fired at the doctor, while also riding a bike, "took some skill". 

Investigators found an extensive intelligence file on his alleged victim at his home. 

Pappas had worked as a peace officer until 1995 with two Houston-area constable officers.  He then worked as a reserve officer for the same constable offices until 2013. 

Dr Hausknecht was described by friends and family as a humble and generous man who adored his patients, volunteered in his community and cared for the environment. 

In 2000, he treated former US president Mr Bush for an irregular heartbeat after he complained about light-headedness.