Member of Punjab Assembly Shamim Akhtar Shahzadi had told police she found her husband Kabir Ahmed,77, lying dead in his house in Samanabad locality when she returned after attending a wedding ceremony last week.
She accused their adopted son Nomi a prime suspect in the FIR. She also told police they had been receiving threats from an unknown caller for sometime.
Police arrested Nomi and also took a call girl into custody.
"We have also taken into custody a call girl, Rahal, who was with Mr Kabir when he suffered cardiac arrest," the investigation official said.
The official further said police found the whereabouts of Rahal through Kabir's cellphone data.