"The fact that the tunnel digging work was going on without being detected for two months, there seems to be some alleged lack of transparency in patrolling and administration by the Sabarmati Central Jail officials which we will investigate," said a senior official of Detection of Crime Branch (DCB) which is conducting the investigations.
A jailbreak planned by Ahmedabad serial blasts case undertrials at the Sabarmati Central Jail was thwarted by prison officials who found on Sunday night an 18-feet-long tunnel dug in the barrack, where 14 of them were lodged.
"We will also check the register to establish who came to visit the blast accused," the official said.
The official further said they were also investigating about how the accused got equipment like iron rods, sharp utensils, pointed asbestos sheets, besides a bulb and the jail map, used for digging the 16.5 feet deep and 26.5 feet wide tunnel.
Out of 68 accused of the serial bomb blasts case, 14 were lodged in the barrack No. 4 called the 'Chhota Chakkar'.
However, the remaining accused will also be interrogated, the official said.
Non-use of Closed Circuit Television Cameras (CCTV) in high security area, where the accused were jailed, has also perturbed the Crime Branch officials.
Crime Branch will also interrogate the accused at its office here for which they will have to revoke Section 268 of the Code of Criminal Procedure (CrPC).
"We will have to revoke Section 268 of the CrPC to bring the accused here and interrogate them," the official said, adding that the accused may be brought here in batches as bringing all of them together could be difficult.
Sources said that Usman Agarbatti, a civil engineer and one of the 14 accused put up in the barrack, is allegedly the mastermind behind the plan, sources said.
The sources said the tunnel was being dug with such finesse that the plan was to link it with an underground sewer line that passed beneath the main gate of the jail premises.
Trial of the serial blasts case is being conducted inside Sabarmati Central Jail, as the state government has invoked section 268 of the CrPC against all the accused in the case, restricting their movement.