TROY – Rensselaer Polytechnic Institute student Yeming Shen made a garbled 911 call six hours before his roommate found him dead from the flu, but the system used to track emergency calls from cellphones could not pinpoint his location.

Troy police and firefighters were able to track the call to the City Station apartment complex where the 28-year-old lived, and spent 45 minutes searching in vain for the apartment from which the call originated.

Defeated, Shen’s would-be rescuers left without finding the person who placed the 911 call at 11:05 a.m. on Feb. 10.

By the time Shen’s roommate came home at 5:45 p.m., the graduate student was dead and the investigation into his cause of death — which briefly triggered unfounded fears of the new coronavirus — was about to get under way.

In the time since, Troy police and firefighters have learned the fruitless search for the 911 caller could have led them to Shen. But a number of factors kept them from potentially saving him.

A quarter-century after the use of cellphones became commonplace in the United States, 911 dispatch systems still have trouble fixing onto the exact locations from which cell users make emergency calls.

Land lines usually allow dispatchers to see who is calling, or at least the exact address from which 911 calls are being made, even when the caller immediately hangs up. Authorities can trace 911 calls from cellphones but such calls are often answered in centralized call centers; dispatchers need to get more information about the location from the person on the other end of the phone. Rescuers can use data from cell towers to refine their searches, but even that data often cannot reveal a caller’s exact location.

Shen’s 911 call was hard to decipher, though authorities couldn't say if that was due to a language barrier, his deteriorating condition or a bad connection. The line went dead before they could learn the caller's identity.

The dispatcher was left with few clues to assist the rescuers: “Difficult to understand. Caller is a male,” is how the Rensselaer County 911 center described the call to police.

The dispatch system was only able to give police and firefighters a general location on Sixth Avenue, where two five-story apartment buildings — City Station East and West — face each other from either side of the street.

“It was just mapped in that area,” Capt. Steve Barker, a police department spokesman, said Wednesday.

Five police officers, three firefighters and a police dog searched the common areas of each floor. But with nothing more than Shen’s telephone number to go on, they couldn’t find his apartment. They called RPI and went to the front desk in City Station West, which is a popular spot for college students to live, but could not learn where in the complex the caller might live.

Another complication involved Shen’s China-based cellphone carrier, police said: U.S. carriers are far more accessible in a fast-moving search for a 911 caller. While Shen’s phone had a 518 area code, there was no way to identify him by name through the phone, Barker said.

An autopsy determined that the graduate student had influenza A — a type of flu that “comes on very sudden and severe,” Rensselaer County Public Health Director Mary Fran Wachunas said.

RPI and county health officials had to work immediately to quell concerns that Shen, a student from China, may have died of the coronavirus discovered in Wuhan, China, in December — even though he had not traveled outside the U.S. for at least 13 months.

“The safety of our students is a top priority at Rensselaer," RPI's administration said in a statement. "As always, following an incident, we review all potentially relevant policies and procedures, and we are currently engaged in that process."