(CNN) -- More than a month after the death of Florida A&M University drum major Robert Champion, investigators are still piecing together what happened that night aboard the band's charter bus. Their work will determine who among the busload of band members will be held responsible for his death.
They're starting to understand more. Last week, Florida's Orange County medical examiner ruled that the 26-year-old man's death was a homicide -- the result of internal bleeding "due to soft tissue hemorrhage" from blunt force trauma sustained on the bus. Investigators believe Champion is the victim of a hazing incident at the hands of other band members.
Investigators aren't saying why Champion might have been hazed. But, they do say that more than 30 people were on board the bus in Orlando, Florida, on November 19. So far, no charges have been filed, but detectives say the majority of witnesses to the incident have been interviewed.
HLN law enforcement analyst Mike Brooks said the entire bus is one big crime scene. He went on board a similar bus to offer some analysis of how the investigation would be handled by police and prosecutors.
"Who did what, when and how they did it, that's what law enforcement is looking for," Brooks said. "The who, what, when, where, why and how."
Brooks noted some questions sheriff's investigators likely will be wrestling with:
-- "Was there any kind of forensic evidence on those uniforms that might have been from the victim, from them hitting him, and maybe blood, any kind of DNA?"
-- "Where did it happen? Did it happen all the way from the front to the rear of the bus?"
-- "How many punches were thrown? Did somebody hit him with ... any musical instrument?"
It's not an investigation that's likely to go quickly.
One band student has told CNN that one of the hazing rituals is called "crossing Bus C." The band member said that the person being hazed walks from the front of the bus to the back of the bus, backward, as band members beat the person.
Brooks said it will like "take quite some time" to determine who was on the bus and where they were situated, and who witnessed the incident. If the witnesses are not forthcoming, he said, "you want to separate each one of them (from the others) to find out exactly what their version of the story is."
"They have to take a look at all of the evidence and all of the statements and decide who is going to be charged, and what are they going to be charged with."
Could more than 30 people be charged with murder?
"Yeah, you could, and that's going to be a decision between investigators and the prosecutor's office," Brooks said.
A "previously healthy" Champion "collapsed and died within an hour of a hazing incident during which he suffered multiple blunt trauma blows to his body," the medical examiner's report states. Champion did not have any broken bones or damage to his organs, according to the report.
"You look at a bus like this, the narrow aisles, the seats so close together," Brooks said. "It's just such tight confines in here and to have to walk from the front to the back of the bus with people just beating the hell out of you -- what must he have gone through?"