Information Minister Sheikh Rashid Ahmed has said evidence so far gathered by the police suggested that no one else but some friends or acquaintances of an Islamabad-based diplomat from Kazakhstan might be responsible for shooting and wounding him. Talking to reporters on Thursday, the minister said culprits could be his own people, as he had returned home late in the night after attending some party.
He accompanied some of his friends, who joined him from the same party or met him on his way home, where they had another party.
"I am sure that law-enforcement agencies would track down the culprits soon," he said.
The diplomat remained in a coma in the hospital after being shot in the head, officials said.
Sapargali Aubakirov, Kazakhstan deputy head in Pakistan, was found in a pool of blood at his house in Islamabad on Wednesday.
"His condition is critical, there is no improvement," the assistant director of the Pakistan Institute of Medical Sciences, Wasim Khawaja, told AFP. "We are not very hopeful," he added.
Police have no immediate clues about a motive or the identity of the attackers but have said there were no signs of a break-in.
Empty bottles of liquor and four party-eaten hamburgers were found lying near Aubakirov, as well as a single empty bullet casing, police said.
The weapon used in the shooting has not been recovered, police added. Aubakirov's car, which had special red diplomatic registration plates, was also missing from the driveway of his bungalow.
Police have formed special investigation teams to trace the culprits but no arrests have been made so far, a local officer said.