The Counter-Terrorism Department claimed to have nailed a notorious target killers, 24NewsHD TV channel reported on Thursday.
According to officials, the arrested was wanted for killing fourteen people including key people from different sects in a bid to sabotage interfaith harmony.
The arrest is named as Syed Ali Raza Naqvi and a key member of a banned outfit, the officials said, adding that in connivance with his gang, he killed three people in Taimuria area while he killed eight people in a Karachi mosque.
He had links with a Syrian group fighting in the Middle East state and escaped aboard, they said, adding that the arrested was on a visit to the homeland and busy re-organising his organisation when a special squad nailed him.
A case has been registered and investigation is on.