Rapid Action Battalion yesterday arrested a suspected "Neo JMB" militant, who was charge-sheeted in a case filed over the 2015 attacks on two mosques inside Bangladesh Navy's Issa Khan Base in Chittagong.

Bablu Rahman, 23, was taken to the port city hours after his arrest in Arappur Bus Stand area of Jhenidah town.

Later, the investigation officer of the case appealed to a Chittagong court to show the accused arrested in the case over the grenade attacks. The court said it would hear the matter at a later date.

Bablu is from Baroipur in Tala upazila of Satkhira. Rab-6 Jhenidah Company Commander Major Monir Ahmed said they arrested the "operative of the Neo JMB's Sarwar-Tamim group" around 7:00am.   

Two attackers from the banned militant outfit detonated bombs at the mosques during Juma prayers on December 18, 2015. The incident left 24 defence personnel and civilians injured. Ten of them were hospitalised.

The attackers were detained and taken in the custody of defence personnel, who launched a departmental investigation into the incident that sent chills down the spine of the nation.

Details of the attack were not available immediately. Some information was found nine months later from the statements of the case filed by Naval Provost Marshal Chittagong Commander M Abu Sayeed. He filed the case with EPZ Police Station on September 3 last year under the Anti-Terrorism Act 2009.

After a long probe, investigation officer Osman Goni (inspector investigation) of EPZ Police Station submitted two charge sheets on October 25 this year against former Navy man Md Shakhawat Hossain, Isha Kha Base's ball pickers Abdul Mannan and Ramjan Ali, and  Abdul Gaffar, brother of Mannan, and Bablu Rahman alias Rony, a mess worker.

With the arrest of Bablu, four accused have been arrested so far. However, Shakhawat is still on the run.

IO Goni yesterday told The Daily Star that the militant outfit had planned to loot firearms from Shaheed Moazzem naval base at Rangamati's Kaptai but failed. Later, they carried out the bomb attacks on the two mosques in Chittagong to show off their strength.

According to the case statement and charge sheets, Chittagong "Neo JMB" chief Raisul Islam Khan alias Fardin alias Noman had supplied the explosives to the JMB members and coordinated the attacks. "Neo JMB" is an offshoot of Jama'atul Mujahideen Bangladesh.

Fardin's name was dropped from the charge sheets as he was killed in a bomb explosion in Bogra on April 3 last year.

The IO said Ramjan, Bablu, and Mannan had taken jobs at the Rangamati naval base's officer's mess as civil employees with the help of Shakhawat. The trio fled the base when letters were sent to their permanent addresses for further verification.

“In the meantime, Shakhawat was transferred to Chittagong Naval Base. With Shakhawat's help, the trio also took jobs in Chittagong," said Goni.

The inspector said arrested Mannan and Ramjan confessed that Bablu, Ramjan and Shakhawat had held a secret meeting with Fardin in the city's Sholoshahar area before the attacks.

In the first attack at the BNS Patenga Mosque inside the Issa Khan Base, Abdul Mannan threw two grenades on the devotees around 1:35pm.

He was detained while trying to get mixed with the panic-stricken devotees, according to the case statement.

Noticing an electric switch in his left wrist, the devotees pulled off the jacket he wore and found a suicide vest inside. Mannan then tried to detonate the vest but failed, the statement added.

Within 10 minutes of the incident, the other attack was carried out on a temporary mosque in the same area. Ramjan, who exploded two grenades there, managed to flee but was caught by navy personnel later.

Navy men recovered a suicide vest and an unexploded grenade from a toilet of a barrack in the afternoon that day.

Merely nine days after the attacks, law enforcers raided a militant den that allegedly belonged to Fardin in Hathazari and recovered an MK-11 semiautomatic sniper rifle, two magazines of the rifle, 5kg gel explosive, 13 army uniform, a pair of badges of army major rank, 252 bullets including 186 of sniper rifle, 25 detonators, bomb-making materials and documents of the outfit.