There will be one more empty seat when the class of 2004 files into the FleetCenter for commencement May 1, but Walter Dedrick’s friends said they’re saving it for him.

For the close-knit group that had come together as freshmen in Speare Hall, the mysterious death of Dedrick was the second tragedy to hit home.

“We all found each other for a reason, we were all pretty tight friends after freshman year,” said Marco Carega, a senior graphic design major and part of the now torn apart group that was once a cluster of doors in a residence hall.

Dedrick was found dead in his apartment at 65 Hemenway St. last Wednesday morning, police said. Less than two years ago, his roommate Dean Doukas overdosed on OxyContin at the same address.

After Doukas’ death, the group relied on each other for support, but the tragedy hit Dedrick the hardest — Doukas, a fellow business major, was his best friend.

Instead of moving out of the Hemenway Street apartment, the friends moved on and Scott Rank moved in.

Rank was a veteran of the group, having lived just doors down from Doukas their freshman year.

Rank, a senior civil engineering major, said he was alarmed Wednesday morning when he realized Dedrick was in the same position in bed as he was the night before, and immediately called 911.

When police arrived, Dedrick was pronounced dead at the scene, but the investigation surrounding his death was just beginning.

David Procopio, spokesman for Suffolk County District Attorney Daniel Conley, said the case has been classified as a “death investigation,” as opposed to a “homicide investigation,” and investigators are looking to determine Dedrick’s whereabouts from 2:30 a.m. Tuesday to later that morning.

After a night of drinking, Dedrick had left his friend’s apartment alone at 2:30 a.m. to return home, according to a report issued by Boston Police. He was not seen again until the next morning, when Rank said he complained of a headache and took some Advil. The two ordered pizza and when Rank checked on him again around midnight, he was passed out on his bed, with the light on in his room. Rank turned the light off and went to bed.

Rank, who had been at Conor Larkin’s with Dedrick Monday night until he left to go home around 12:30 a.m., said he knew of no incidents which would have led to bruises Dedrick’s father said covered his son’s body.

When Rank asked him about the bruise on his head the next day, Dedrick could not remember where it originated.

Dedrick’s father, Warren, who flew up to Boston from Florida Thursday to view his son’s body and take care of arrangements, said he had “a massive number of bruises all over his body, legs, knees, arms, hands and a very, very large bruise on the left side of the face, two inches wide, four or five inches long.”

However, while his father also said he had a slow bleed in his head and internal injuries, the actual cause of death is yet to be determined, pending the results of toxicology reports.

While the cause of Dedrick’s death may remain unknown for up to four weeks, his father decided to retain a medical examiner of his own. Dedrick’s uncle, an associate anesthesiologist professor at Harvard University, suggested that although the medical examiners in Massachusetts are some of the best in the country, he should still get a second opinion.

Warren Dedrick, who spoke with his son Tuesday as he did every day, said his son did not mention he had a headache, though he sounded “a little lethargic.”

On Wednesday morning when he received the news, he said he was sitting at a business meeting in New Orleans, talking to colleagues about his son.

With graduation looming only a few weeks away, Dedrick, a business administration major, had secured a job in Ft. Lauderdale, Fla., near his father’s Key West home.

“Without me knowing it, he applied for a job at one of my companies and obviously got the job – it’d be kind of hard for someone to say no I guess,” his father said.

He said he did not even know, until one of his employees mentioned it, that his son was set to start working for the medical debt purchasing company, one of 13 companies Warren owns, May 6.

Warren Dedrick then flew to Fairfax, Va. to tell Dedrick’s mother and sister the news in person before arriving in Boston Thursday.

To cater to the schedules of Dedrick’s large social circle, Mr. Dedrick set up a memorial service Sunday to honor his son’s life. He said nearly 200 people attended, including 65 people from out of town.

Dedrick’s former girlfriend Dorothy Castiglioni, a senior criminal justice major, spoke at the service, reading from a song Dedrick had written to his family and friends.

Castiglioni, who had met Dedrick exactly three years before the day he died, said speaking at the funeral was “one of the worst days of my life.”

“He made everybody laugh,” Castiglioni said. “Anything he said would catch on with people. The next day, everybody was saying what he was saying the night before.”

The group had just spent the winter holiday in Key West together at Dedrick’s father’s house.

“He wasn’t just a good friend; he was the best,” Carega said.

The deaths of Dedrick and Doukas were not the first tragedies to rip through the class of 2004 — Candace Lee Williams died in the September 11 attacks as a passenger on American Airlines flight 11. Castiglioni also knew Williams.

This is also the sixth time Northeastern has had to deal with the death of a student this academic year.

“This has been one of the most painful series of losses in our history,” said Student Government Association President Michael Romano. “Whether you knew one of them, all of them, or none of them, I think this is resonating across the board.”