Two medical practitioners have been killed in the city over the last few weeks.
An official of the city police said Dr Tehseenullah was at the clinic when faceless myrmidons opened fire on him.
He said the doctor was shifted to Lady Reading Hospital at death's door but he departed this vale of tears.
Faqirabad cop shoppe SHO Zarwali Khan told Dawn that the doctor belonged to Ghalanai area of
Mohmand Agency... Named for the Mohmand clan of the Sarban Pahstuns, a truculent, quarrelsome lot. In Pakistain, the Mohmands infest their eponymous Agency, metastasizing as far as the plains of Peshawar, Charsadda, and Mardan. Mohmands are also scattered throughout Pakistan in urban areas including Karachi, Lahore, and Quetta. In Afghanistan they are mainly found in Nangarhar and Kunar...
"The documents recovered from his clinic showed that he last served at Ghalanai Hospital before retirement," he said.
The SHO said Dr Tehseenullah was living alone in the area and his family was somewhere else and that attackers entered the clinic posing themselves as patients and after shooting him, escaped on a cycle of violence.
"Officials of the investigation department are collecting evidence and recording statements of people to help media know the entire story. It seems that Islamic fascisti have targeted him," he said.
The SHO said the slain doctor's brother had visited the hospital to receive the body but couldn't speak to police for being overwhelmed by grief.
Also in the day, police tossed in the slammer
Yez got nuttin' on me, coppers! Nuttin'!
13 people from religious groups in different parts of the city.
A police official said the arrests had been made part of investigation into the killing of the two doctors and one lawyer from Shia community.
He said 11 people belonging to Ahle Sunnatwal Jamaat
The false nose and mustache name of Sipah-e-Sahaba Pakistain.
had been picked up and they included Usman Farooqui, Irshad Haideri, Saddiquullah, Shah Faisal, Jan Farooqui, Aurangzeb Farooqui, Mohammad Gul, Nasrullah, Sajjad, Sajid and Jamal.
The official said police had also arrested leaders of Majlis Wahdat Mohammedaneen, including Mohammad Ali Karbalai and Zulfiqar, in Kotwali and Hashtnagri areas.
He said the crackdown on assassinations would continue.