Police on Tuesday questioned an NIT student in connection with the suspected murder of his batch mate Akash Ranjan, who died under mysterious circumstances on Monday morning.

The police, however, didn't arrest the boy, who has been named in the case lodged by family members of Akash. The police claimed that preliminary investigations did not point to the boy's involvement in the death.

"The police on Tuesday quizzed Akash's college mate in connection with the suspected murder of Akash. But as there was no direct evidence against the boy, we have not arrested him," Patna senior superintendent of police Manu Maharaaj said.

The officer added that Akash had not gone to attend the birthday party of a common friend being hosted by the accused student on Saturday.

Akash's relatives had on Monday said he had informed his younger brother Ashish Ranjan that he was going to his friend's flat on Saturday.

Even Akash's family members are now conceding that the involvement of the student they have named in the FIR is doubtful.

Ashish, the younger brother of Akash, said: "We gave the name of Akash's college mate in the FIR as before leaving his house, Akash told us he was going to his house. But given the relationship between the two, we doubt that he was directly involved in the incident."

Akash, 22, a third-year student of mechanical engineering, died at a city hospital on Monday morning after which the police registered a case of suspected murder against his college friend based on statements of his family members.

The Telegraph has withheld the name of the accused student since his involvement in Akash's death is yet to be established.

Police sources said they are now probing other aspects of the case.

A senior official at Agamkuan police station, where the FIR was lodged, said: "The police are looking into other angles such as suicide or the involvement of someone else."

Police sources said Akash had been depressed for the past few months as he had not fared well in several engineering papers.

The boy was worried about his career prospects and had once tried to commit suicide by consuming poisonous liquid, the police sources said.

A.N. Sinha, the head of the mechanical engineering branch at NIT Patna, too said: "The boy (Akash) was an average student and his friends have informed that he was suffering from depression."

On Saturday too, Akash had written an internal exam and was upset, the police sources said. After his test, Akash went to Ashish's flat at Munnachak.

He left around 8.30pm, saying he was going to attend a birthday party at his friend's house in the same locality.

Later Ashish spotted Akash lying in a semi-conscious state near Care Hospital. They took Akash to Nobel Hospital, where the doctors said he should be shifted to some other hospital.

The police have also discovered that Akash was in regular contact with a girl from Uttar Pradesh for the past two months.

The police have asked the telecom service provider for details to help them track down the girl.