Authorities were tipped off to Pappas’ identity Tuesday. Officers stopped at his house that night after learning he had sent a text message to someone saying that he was going to kill himself, but he was not home. He has not been seen for more than 24 hours, Acevedo said.
Officials warned people not to approach Pappas, who was described as well-armed and suicidal.
“This man is dangerous. This man’s capable. This man has some skills,” Acevedo said. “We know he had ... a lot of firearms -- more than one, I can tell you that. ... He's very dangerous and we need to get him into custody.”
Authorities earlier said it appeared Hausknecht had been targeted.
In a statement issued after the shooting Bush spokesman Jim McGrath said the 41st president was "deeply saddened by the tragic circumstances surrounding the untimely passing of Dr. Mark Hausknect."
"Mark was a fantastic cardiologist and a good man," Bush said. "I will always be grateful for his exceptional, compassionate care. His family is in our prayers.”