Jahangir Alam, 32, was apprehended Friday night in the Tangail district, about 100 kilometers (62 miles) northwest of Dhaka, Shahidul Hoque, inspector general of the Bangladesh police, told CNN. Alam appeared in court Saturday.
Two police officers and 21 captives were killed
in July when armed gunmen stormed an upscale cafe and took hostages.
Another alleged attack planner, Nurul Islam Marzan, was killed in a shootout with police
a week ago.
Alam is alleged to be a highly ranked leader of Jamaatul Mujahideen Bangladesh
, or JMB, a local terror group that authorities accuse of being responsible for the attack, though ISIS also claimed responsibility.
Alam's suspected role was to train some of the attackers in the cafe assault, Hoque said.
He also is suspected of involvement in planning attacks on Hindu and Christian priests in the recent years, Hoque said, and allegedly led the killings of Japanese citizen Hoshi Kunio
and Rajshahi University professor Rezaul Karim Siddique
Sunni Muslim extremist group
Two other men thought to be main organizers behind the cafe attack were killed last year.
Bangladeshi-Canadian Tamim Ahmed Chowdhury -- considered the mastermind, according to Hoque
-- was killed in August
, and Abdur Rahman died in October
after jumping off a fifth-floor balcony while trying to escape police.
Alam was a "close aide" of Chowdhury's, Hoque said.
JMB is a Sunni Muslim extremist group that has pledged its allegiance to ISIS. It aims to transform Bangladesh into an Islamic state based on Sharia law
Although Bangladesh has dealt with terror attacks in the past, with secular bloggers, Hindu priests and others killed in cold blood, the July 1 cafe attack was of a much larger scale.
The assailants appeared to be
"normal, regular guys," and their target was the Holey Artisan Bakery in the city's Gulshan district, one of Dhaka's most affluent neighborhoods and a diplomatic enclave.
The bakery reopened last week at a different venue a few blocks away from its original location.
Co-owner Ali Arsalan told CNN that it was a smaller, mostly takeaway operation inside a boutique supermarket next to a police station. He is also considering opening a new restaurant elsewhere -- but only if its safety can be assured.
"Security is our paramount concern," Arsalan said. "We just don't want to run the risk of a similar thing happening again. We will do everything we can to make sure the customers, ourselves, our staff are well protected."