The police of Providence, Rhode Island, has launched a massive search operation to find Tripathi, while his friends have not only been doing their own search, putting up posters across the city, but also have launched a Facebook page to find him.
Lead investigator detective Mark Sacco said "no solid leads" have been found so far.
Tripathi's cellphone, credit card, ID and other personal things were found in his room.
FBI declined to comment on the investigation, except for saying that it is assisting the local police in search of the missing student.
According to the Facebook Page set up by family, Tripathi who went missing from his Angell Street residence since Saturday morning is 6'0, 130 pounds, with brown eyes and short brown hair.
He left wearing blue jeans, a Philadelphia Eagles beanie, and a black sweatshirt. He is essentially off the grid since he does not have his ID, wallet, or cell phone.
"Sunil has been struggling with depression since he took a leave of absence from Brown last year. A note suggestive of suicidal intent left behind in his apartment has his family extremely worried," the family said, adding that they are currently in Providence, helping the police search for him.
"Sunil is a kind, gentle, and shy young man. All we want is for him to return safe and well," the family said.
Tripathi, a philosophy major, was on approved leave from the University. Early on March 17, Brown's Department of Public Safety received a report of a missing person.
"The missing person report is being handled by the Providence Police Department with the full cooperation of Brown police officers and University staff. The Office of Student Life has been in touch with Sunil's family, and our concerns are first and foremost with Sunil and his family.
Tripathi's sister Sangeeta said her brother had "no exceptional plans" that weekend and that it was "completely atypical" of him to disappear without contacting anyone.
"Between family and friends, we are in constant contact with him," 30-year-old Sangeeta said. "We became worried when he didn't respond to many missed calls."
The search has focused in the past week on hospitals, stores, parks and other public spaces where Tripathi could be, but authorities have found no signs of him.
The search, which has been spearheaded by the Providence Police Department and the Brown University Department of Public Safety, has now expanded to Boston, Connecticut, New York and Philadelphia, according to a statement from the school.
"(It's) on the small hope he just decided to go somewhere and is OK. People have been posting fliers and visiting places a young person without an ID or money would go," she said.
"We're a very, very close family and when we heard (he was missing), we were trying to frantically look for photos. We had trouble finding a photo (where) we all weren't so physically close in the image," she said.
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