Presidency University’s mentor group posted a Bengali new year message demanding a “thorough and impartial investigation” into Wednesday’s vandalism even as police landed up on the campus unannounced on a holiday to question people within instead of the perpetrators outside.

“We want to see the guilty swiftly brought to book,” the mentor group headed by Harvard professor Sugata Bose posted on its website www.pmg.org.in on Monday.

The only sign of an investigation being underway was the police’s entry into Presidency to seek guard Santosh “Pappu” Singh’s bank details, among other things.

Pappu, a third-generation guard at the college-turned-university, has already been through several hours of grilling on the basis of industries minister Partha Chatterjee’s allegation that he had provoked the vandalism by a mob flaunting Trinamul flags.

Siddhartha Dutta, the officer-in-charge of Jorasanko police station, and sub-inspector J. Midda stepped into the campus around 2.30pm on Monday and said they wanted to question Pappu. He wasn’t there, so they spoke to his wife Rekha and took his bank details from her.

“She was puzzled but gave what they asked for out of fear,” a source said.

The officers took pictures of the logbook containing details of Pappu’s duty hours with a mobile-phone camera and instructed the other members of the security staff not to make any new entry on Tuesday.

One of the officers said they would speak to the university authorities on Tuesday about the entries in the logbook on April 10, when the campus was invaded.

“In a vandalism case, where this man (Pappu) is in no way connected to the accused, why should you require his bank details? Such things are bound to scare away key witnesses,” said a senior police officer not connected with the investigation.

Officer-in-charge Dutta declined to say how Pappu’s bank account might be connected to the vandalism. “I won’t say anything on this,” he told Metro in the evening.

University officials said the police should have informed the authorities before entering the campus on a holiday.

A police veteran who did not wish to be named backed the university’s stand. “There is no legal bar on the police’s entry for the sake of a probe but decorum demands that the police inform the authorities of an educational institution before stepping in. This is the reason why police are posted outside a college campus even during student polls,” he said.

Sources said officer-in-charge Dutta asked Pappu’s wife how much he earned in a month. He and colleague Midda also spoke to some members of the cleaning staff.

“The university’s guards told us that officers from Jorasanko police station wanted to meet Pappu. As he was not there, they spoke to his wife Rekha and took his bank details from her,” registrar Prabir Dasgupta confirmed.

Police officers not associated with the probe pointed out that the investigation team hadn’t completed one of the basic formalities: tagging the complaint lodged by student Debarshi Chakraborty with the main FIR.

Debarshi has named some of the outsiders who had assaulted him while vandalising the campus on April 10. His allegations corroborate the version given by the university authorities in the FIR.

Trinamul councillor Partha Bose and the general secretary of the party’s student wing, Tamaghna Ghosh, are among the names in the Presidency student’s complaint.

Bose and Ghosh are also seen in photographs and video footage of the incident, standing alongside the vandals carrying Trinamul flags outside the university gate minutes before it was broken open.

The rule book stipulates that if there are two complaints about a common incident, the police should tag one complaint with the main FIR.

Debarshi’s complaint was registered as an entry in the general diary, excluding it from the ambit of the Indian Penal Code (IPC). If the complaint is tagged with the FIR, the police would need to start a case against the accused identified by the complainant.