By Jeff Gammage, INQUIRER STAFF WRITER

The thumpa-thumpa beat of rap music blasted from the car radio as Christopher Adams sat at a red light on Allegheny Avenue.

Police Officer George Holcombe could hear the sound from 50 yards away. He pulled up behind the blue Mazda and signaled for Adams to pull over. Holcombe was going to tell the young man to turn down the volume.

It was the kind of routine stop that happens every day in Philadelphia. But this one, on a sunny spring afternoon in March 1994, ended in tragedy.

Adams was driving a stolen car, but Holcombe didn't know that. Adams pulled over for a few seconds, then hit the gas and tore off. Holcombe chased him through the residential streets of Tioga at speeds up to 60 m.p.h.

Adams bailed out of his car on a side street, and Holcombe ran him down, with his gun drawn. Moments later, Adams , 21, who had neither a weapon nor a criminal record, lay dying of a bullet wound to the back of the head.

The Police Department and a Philadelphia grand jury ruled the shooting an accident. Adams ' parents say otherwise. In a federal civil rights suit that seeks unspecified monetary damages, they contend that Holcombe shot their son deliberately.

The wrongful-death suit against the city, Holcombe and Police Commissioner Richard Neal is scheduled to go to trial in U.S. District Court today, nearly two years to the day since Adams was killed.

At issue is the entire manner in which Philadelphia police officers are trained, armed and supervised in their weaponry. The suit contends that the shooting was not a random tragedy, but the inevitable result of flawed policies on the use of firearms. Neal is among a parade of top commanders expected to testify.

In court documents, city officials reject the Adamses' assertions, saying that officers are well-trained and governed by firearms regulations that are strictly enforced.

The parents are looking to the trial to resolve lingering questions about how their son died.

In a sworn deposition taken by the family's lawyer in November, and in an earlier interview with internal-affairs investigators, Holcombe said he drew his pistol that day because he feared for his safety. When Adams got out of the car, Holcombe said, the young man reached back inside as if to grab a weapon.

Two other police officers who were at the scene, one of whom described himself as Holcombe 's friend, said in depositions that they saw Adams make no such movement.

Holcombe 's supervisor, who spoke with the officer minutes after the shooting, said he could not recall Holcombe telling him that Adams had reached back into the Mazda.

No gun was found on Adams or in the car.

``It's not a money issue. It's a justice issue,'' said Adams ' father, Peter, who runs a printing business in the city's Powelton section. ``You don't just shoot people for running away and playing the radio too loud.''

The family's lawyer, Scott Bennett, plans to present testimony from James Fyfe, a criminology professor at Temple University. Fyfe said he will testify that Philadelphia police have shown a pattern, dating to 1979, of shooting unarmed suspects or bystanders.

In court documents, city officials point out that the department punished Holcombe over the shooting - he was suspended three weeks without pay for ``improper use, handling or display of firearms'' - and that the grand jury declined to indict him on criminal charges.

Deputy City Solicitor Jeffrey Scott, who represents Holcombe and the Police Department, said he could not discuss pending litigation. Neal declined to comment on the same grounds.

Holcombe , 24, a four-year veteran now assigned to the 24th Police District in Kensington, did not respond to requests for an interview.

Several officers who saw Holcombe at the scene of the shooting said he was distraught and remorseful, weeping in his patrol car. ``He said he didn't mean to shoot the guy,'' said Lt. Steven O'Neill, then Holcombe 's supervisor.

* Adams spent his early years in Philadelphia and went to Springfield High School in Montgomery County, graduating in 1991. He didn't want to spend money on college, his father said, because he had no definite career in mind. So he worked at McDonald's restaurants and sorted mail at Bryn Mawr College while nursing an interest in computers and electronics.

Adams took classes at the city's Computer Learning Center and graduated in 1992, but couldn't find a job. The heavyset young man - he packed 263 pounds on a 5-foot-7 frame - spent much of his time doing volunteer work at the Salvation Army center in West Philadelphia, helping to organize youth tee-ball leagues and other programs.

``He was quite an invaluable asset,'' said Salvation Army Capt. Charles Roberts.

The shooting occurred on March 20, 1994. Trial depositions, police documents, autopsy reports and court filings provide a rich narrative of what happened that afternoon in Tioga.

Adams , wearing green pants, a purple jacket and a purple baseball cap, was stopped on Allegheny Avenue at 25th Street about 4:30 p.m. He was bobbing his head to the beat of the music thundering from the car radio.

The Mazda he was driving had been reported stolen a month earlier. Police do not know whether Adams stole the vehicle or how he came to be driving it. His parents said their son had never been in trouble with the law.

Holcombe heard the music even before he saw the car. When the light changed, Adams drove east through the intersection. Holcombe turned on his siren and flashing lights. Adams pulled over briefly between 24th and 22d Streets, but then sped off.

Officer Jihad Ali, stopped at 22d and Allegheny, heard the siren and then saw the Mazda flash by, followed by Holcombe 's cruiser. Ali joined the pursuit. Officer Magdalen Clarke, on patrol at Allegheny and 21st Street, heard the radio report of the chase and saw the cars rush past. She followed, too.

Adams turned left onto 21st Street, heading the wrong way up a one-way street, and turned right onto Madison Street, where he was blocked by a double-parked car at Woodstock Street. The police cars pulled in behind.

It is at that point that accounts diverge, and Holcombe 's differs from those of the two other officers and O'Neill, the supervisor to whom Holcombe gave his first account of the incident.

O'Neill said Holcombe told him that he couldn't see Adams ' right side or right arm when the young man got out of the car.

Police internal-affairs investigators interviewed Holcombe eight months later. In that interview, and in a deposition last November, the officer added significant details.

Holcombe said that during the car chase, he came to suspect the Mazda was stolen - in part, the officer said, because the driver seemed not to have adjusted the car seat for his size. After Adams stopped on Woodstock Street, Holcombe said, the young man leaned over into the passenger side of the car, disappearing from view for a few seconds.

``That's when I drew my gun,'' the officer said in the deposition.

Holcombe said that Adams got out, reached back into the car, and started running. He kept his right hand in front of him, not swinging both arms in a normal running motion, Holcombe said.

``I thought he was carrying a weapon in his right hand,'' the officer said.

Holcombe , a competitive weight lifter, quickly caught up with the stout young man. He said that he grabbed Adams around the shoulder with his left hand, that Adams tried to pull away, and that they began to tumble, first forward and then backward.

``Just instinctively, I reached up with my right hand, forgetting that I had the gun in the hand, and tried to brace myself for the fall,'' Holcombe said.

The bullet that exploded from his Glock semiautomatic entered the back of Adams ' head and exited over his right ear. Holcombe later said that at first, he didn't even realize he had fired - that when he heard the shot, he thought someone was shooting at him.

Clarke ran to where Adams lay and told him rescue units were on the way. ``I believe he heard me,'' the officer said. ``When I started talking to him, he looked up at me.''

Adams was dead on arrival at Temple University Hospital.

In his deposition, Ali said he had watched Adams get out of the car.

``Did you see him reach back into the car with his right hand?'' asked the Adamses' attorney.

``I didn't see that. . . . I was looking at him,'' the officer answered.

Clarke was also unequivocal.

``Did you ever see him reach back into the car after he got out of the car?'' she was asked.

``No,'' she answered.

In his deposition, O'Neill said he had no recollection of Holcombe telling him that Adams had ducked down in the car before getting out, or that he had reached back inside the vehicle as he exited. If he had remembered being told that, O'Neill said, he would have put it in his report.

Police regulations state that an officer should draw his weapon when he believes he or someone else is facing serious injury or death, or to stop a fleeing felon - someone who has used or is about to use a deadly weapon, or who has committed a serious crime, such as murder, manslaughter or rape.

In the deposition, Holcombe said he did not believe that he violated police regulations that day. He said that his only aim was to catch Adams , and that he did not recall putting his finger on the trigger. He acknowledged that Adams never turned toward him, shouted a threat or tried to take his gun.

``My plan was not to shoot him,'' Holcombe said.

* Fyfe, the Temple criminologist retained by the Adamses, said in a 13-page report on the incident that ``inconsistencies, unresolved questions and improbabilities'' in the police accounts ``should have created great doubt that this incident occurred as described by Officer Holcombe .''

A most telling fact, Fyfe said, was that no weapon was found in the car or on Adams .

Fyfe said police officers should draw their guns only when they have reason to anticipate a threat of death or serious injury.

``The evidence available to Officer Holcombe in this matter - young man in old car plays radio too loud and flees when police attempt to stop him - certainly did not reach such a level,'' Fyfe said in the report.

Three hundred people went to Adams ' funeral, mourning a young man whose potential was largely untapped.

``We lost a very caring, sharing family member,'' said Margie Adams , his stepmother since he was 10. ``And we lost what he could have been to us, in terms of getting married and having grandchildren.''

``I lost my son and it hurts,'' Peter Adams said. ``It hurts terribly. It hurts that you can shoot somebody in the back of the head, and they say it's an accident.''