Atiullah (22), a native of Bihar, was arrested following an encounter near Barauli bridge under Banna Devi police station in Aligarh on Tuesday night, an STF release said.
Atiullah, who was carrying a cash reward of Rs 50,000, was wanted in 11 criminal cases. A .32 bore pistol and cartridges were recovered from his possession, the release added.
Atiullah, who had come into contact with Munir during the 2012 Aligarh Muslim University elections, has told the police that both had fled the city in September, 2015 following a murder on the Aligarh Muslim University campus, the release added.
Subsequently, he had met Munir in Nepal but was not aware of his whereabouts since then, the release said, adding that a case has been registered and further investigation was on.
Tanzil Ahmed was gunned down by armed assailants in Bijnor district in Uttar Pradesh on the night of April 2 when he was returning home with his wife and two children from a wedding.
The post-mortem report said Ahmed had received 21 bullet injuries. His wife Farzana too succumbed to bullet injuries 10 days after the incident in AIIMS in New Delhi.
The main accused in the case, Munir, a resident of Sahaspur and a history-sheeter, is still on the run.
Ahmed had handled several cases related to the banned Indian Mujahideen outfit, including the arrest and probe of the outfit's India chief, Yasin Bhatkal.
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