Following a hit-and-run accident Sunday morning, Andromahi “Mahi” Trivellas’ ’11 condition has been re-classified as serious and not stable, a Yale-New Haven Hospital spokesperson said Monday night.

Just hours earlier, New Haven Police Captain Stephen Verrelli said her condition had been upgraded to “serious but stable” and non-life-threatening.

Meanwhile, police may have discovered the vehicle that struck the Branford freshman early Sunday morning, Verrelli said at a press conference outside New Haven Police Department headquarters Monday afternoon. Investigators are still questioning eyewitnesses and the owner of the found car and examining material evidence, he said.

Trivellas was rushed to the hospital early Sunday morning for head and spinal injuries after being struck by car at 1:05 a.m. at the intersection of York and Elm streets. Witnesses of the accident said Trivellas was crumpled over and screaming as emergency workers tended to her.

Verrelli said there is still no indication of who was at fault. The signals at the intersection were “suitable and substantial” at the time of the accident, but it is “too early to tell” who had the right of way, he said. Several eyewitnesses to the hit-and-run are still being interviewed, Verrelli said, and completion of the investigation may take months.

At the press conference, Verrelli said the NHPD had discovered a “vehicle of interest” that matches eyewitness descriptions of the car. At approximately noon on Monday, the “vehicle of interest” found near Edgewood Avenue and Hobart Street was brought to NHPD’s attention by a former police officer, he said.

Verrelli said the car is legally registered and has not been reported as stolen. He said police are in contact with the registered owner but declined to comment on exterior damage to the car and whether or not such damage would match the profile of a hit-and-run.

The car seen at the incident, which was described as a large, white sedan with a blue top — possibly an Oldsmobile or a Crown Victoria — “did not stop at all” after it struck Trivellas, Verrelli said.

The NHPD is also looking into obtaining video footage of the street from businesses and restaurants near the intersection, Verrelli said.

Mohamed Masaud, a clerk at Gourmet Heaven, located on 15 Broadway, said the store had a video camera that points out toward the intersection of York and Elm streets. Police are now in possession of the surveillance tapes, which Masaud said he thinks are clear enough to reveal license plate numbers.

“We gave it to [police] this morning,” he said. “I’m sure that it’s already helped.”

Tyrhonda Epps, a shift supervisor at Au Bon Pain — the business closest to the site of the accident — said she was working at the restaurant Saturday night. Epps said none of its employees witnessed the crash and the store does not have a surveillance camera.

Epps said police had not asked her for information.

Verrelli said because the intersection has such a high volume of both automobile and pedestrian traffic, residents should be especially cautious when travelling through the area — particularly when the crosswalk is red.

Two of Trivellas’ roommates declined to comment on her condition. Her twin sister Myra Trivellas ’11, a resident of Saybrook College, could not be reached for comment.

Trivellas’ parents, who have been with her at the hospital since the accident, issued a public statement thanking friends and hospital staff for their support.

Verrelli requested that anyone with information about the Sunday hit-and-run contact the NHPD immediately.