This weekend, the Yale College Class of 1999 will descend on campus for its 15th reunion. One would-be graduate of that class will be notably absent: Suzanne Jovin ’99, the Yale College senior who was murdered — stabbed 17 times in the back of the head and neck — on Dec. 4, 1998.

Fifteen years later, the culprit of this shocking crime remains unknown. As Jovin’s classmates congregate on campus, investigators in charge of the cold case are urging members of the class to think back to where they were on that unusually warm December evening, when their classmate was found bleeding to death on the corner of Edgehill Avenue and East Rock Road, just under two miles from Phelps Gate.

Deputy Chief State’s Attorney John Russotto said the investigation depends on the assistance of additional witnesses, particularly people who may have been in the vicinity of Edgehill and East Rock between 9 and 10 p.m. Jovin was discovered around 9:55 p.m and declared dead on arrival at Yale-New Haven Hospital.

“The question we’re trying to have answered is why Suzanne Jovin was in that area at that time,” Russotto said, noting that she was seen by Phelps Gate at 9:20 p.m., leaving little time for her to have traveled two miles northeast of campus.

Over the course of the intervening 40 minutes, a man and a woman were heard arguing at three separate locations — first at 750 Whitney Avenue, then on East Rock Road near the intersection with Whitney Avenue and finally at the corner where Jovin was found bleeding to death.

Being back on campus may jog the memories of Jovin’s classmates, Russotto said.

“We’re looking for friends, but also for acquaintances and passers-by — anybody who might know whether Ms. Jovin was one of the people heard arguing, and if so, whom she was with,” Russotto said.

The second focus of the investigation is on the identity of the individual to whom Jovin lent Graduate Record Examinations (GRE) study materials, and from whom she was allegedly planning to pick them up, according to an email message she sent in German at 9:02 p.m.

Maybe a returning member of the class of 1999 knows someone who took the GREs that year, Russotto speculated, or maybe the actual person to whom the books were on loan will be at Yale this weekend, with insight about Jovin’s whereabouts that night.

“These are the two things we’re trying to pin down,” Russotto said. “The hope is that someone can help us fill in the blanks.”

In a letter to the Class of 1999, David Cameron, a political scientist at Yale, notes the importance of the identity of a man, “running as if his life depended on it,” seen by a Hamden woman at around 10 p.m. in the vicinity of Huntington Street and Whitney Avenue, two blocks from the crime scene. The woman told police the running man was white with blond hair, physically fit and seemed to be in his 20s or 30s.

In addition to the Connecticut office of the chief state’s attorney, the New Haven state’s attorney’s office and the New Haven Police Department are still involved in probing the case, Russotto said.