Siddiqui is facing charges of firing at Mohabbat-i-Sindh rally in Karachi on May 22, 2012.
The court also declared four other culprits as proclaimed offender. They are; Arif, Adnan, Naeem, Ikhlas.
At least 12 people had lost their lives when the rally came under gunmen attack in Saddar. The rally was taken out by Awami Tehreek.
In May this year, reports were going rounds that the UAE authorities have apprehended former member of MQM Hammad Siddiqui from Abu Dhabi.
UAE authorities had arrested two men in connection with Imran Farooq murder and money laundering cases.
It was reported that political quarters in Dubai have also confirmed the name of the arrested man as Hammad Siddiqui.
Hammad Siddiqui had been working as the in-charge of the Karachi Tanzeemi Committee (KTC) of MQM, however his party membership was suspended in 2013 for violating discipline, and later Siddiqui moved to UAE.