KARACHI: A dentist allegedly linked to militant group Al Qaeda as well as Safoora Goth accused Saad Aziz was arrested after an encounter early Sunday night, Preedy police station officials said today.

Preedy police booked suspect Dr Usman in two cases pertaining to attacking police and possession of illegal weapons.

Counter-Terrorism Department (CTD) head Raja Umer Khattab said Dr Usman was familiar with Saad Aziz, the main accused in the Safoora Goth massacre, but played no direct role in the attack.

Khattab said Dr Usman is an Al Qaeda facilitator with links to Al Qaeda Punjab representatives Haris, who has been arrested, and Ali Rehman, who is still at large.

At least 43 people were killed and 13 others wounded in a barbaric attack on members of the Ismaili community in Karachi's Safoora Goth area on May 14, 2015. Six gunmen entered a bus carrying 60 people and executed 43 passengers at close-range, according to Sindh Police Inspector General Ghulam Haider Jamali.

Explore: Anatomy of a murder

Saad Aziz alias Tin Tin alias John, the main accused in the Safoora Goth case, is the alleged mastermind of the of the attack on activist Sabeen Mahmud and is suspected of involvement in terrorist activities since 2009. People who knew the former Institute of Business Administration graduate say he may have grown religious over time.

Sindh Chief Minister Qaim earlier said Saad Aziz "is a trained militant with expertise in producing different types of literature. He provided funds for terror activities in the city".

Know more: From IBA graduate to 'terror suspect'?