Confirming the development on Thursday, officials said Shah was taken into custody in Lodhran during a raid by the cybercrime wing of the agency.
It occurred after late Liaquat's daughter complained about Shah uploading a controversial video online.
On the other hand, Shah's mother Salma Bibi said police personnel barged into their house to handcuff her daughter.
She also said that she is being keep in the dark on Shah's whereabouts.
The MNA died in Karachi on June 9 under mysterious circumstances. The causes behind his demise could not be ascertained after a court ruled out an autopsy.