Veterinary doctor Ashfaq Ahmed, 68, was shot dead on Friday in the Sabzazar area of Lahore in what appeared to be a faith-based targeted attack.
The doctor, who was from the Ahmadi community, was being driven by his grandson when a motorcyclist pulled up next to their car and fired at point-blank range, killing him on the spot.
His grandson, Shahzeb, remained unhurt, while the attacker, who was wearing a helmet, fled the scene.
Prof Dr Ashfaq Ahmed had retired as a professor from Lahore University of Veterinary and Animal Sciences. He held a PhD in food and nutrition.
For the police, it was too early to say whether he was targeted because of his faith.
However, Salim Uddin, a spokesperson for the Jamaat-i-Ahmadiyya Pakistan, condemned the attack and protested that the doctor was targeted because of his faith.
"In a span of 10 days, this has been the second killing of an Ahmadi. There is a campaign of hate against the Ahmediya community and as a cost, innocent people are killed.
On the one hand, the government boasts about the Operation Radd-ul-Fasaad and on the other, people are being killed along religious lines in broad daylight," read an excerpt from a press release issued by the Anjum-i-Ahmadiyya Pakistan.
On March 30, a prominent Ahmadi lawyer, Malik Saleem Latif, was fatally wounded in a gun attack claimed by the banned sectarian outfit Lashkar-e-Jhangvi. Latif was also a cousin of the late Prof Abdus Salam, Pakistan's first Nobel Laureate.