On that hot June day three months ago, Ron Settles seemed on top of his world, a college football star looking toward his best season and a possible contract with the Dallas Cowboys.

But on his way to a summer job about 11:30 a.m., the 21-year-old Settles was stopped for speeding in the oil-pump-dotted city of Signal Hill. Three hours later he was dead.

Now, a coroner's jury has reversed an official verdict of suicide, finding that the black football player died "at the hands of another." The FBI and the Los Angeles County district attorney are investigating the case. Settles' parents have filed a $50 million claim against the city and Southern Californians are wondering again about the hiring and firing practices of their overworked and sometimes violence-prone police departments.

Police say when he was stopped June 2, Settles refused to show his driver's license, tried to pull a knife on officers, resisted arrest and was found to have cocaine in his car. They say he hanged himself with a mattress cover found in his jail cell.

The officer who stopped Settles, Jerry Lee Brown, a civilian woman riding with him, and five other police personnel who assisted in the arrest or were at the station when Settles was brought in invoked the Fifth Amendment against self-incrimination and declined to answer questions at the coroner's inquest.

An attorney for Settles' family introduced evidence of earlier violent incidents involving Brown and said the officer had been hired by Signal Hill, which has only 26 officers, after being fired by the Los Angeles city police department. The one white and four black coroner's jurors who voted that Settles had not killed himself said afterwards they were strongly influenced by the officers' failure to testify. Four other jurors, all white, voted to support the coroner's original verdict of suicide.

Settles' family and friends, plus two members of the Los Angeles County grand jury, packed the small hearing room during the 10 days of the inquest. The family and friends cried out with joy when the verdict rejecting the police's and coroner's suicide finding was announced, for they have insisted the young man about to begin his senior year at California State University at Long Beach had everything to live for.

"This renews my faith in humanity," said Helen Settles, the athlete's mother. "The Bible says, if you take one step, God will take two."

Her husband, Donnell Settles, said, "We just hope that what happened in this case will stop these things from happening again."

Settles was already his school's fourth all-time leading rusher, gaining 1,323 yards with an average 4.4 per carry. His family said he had gotten a letter expressing interest from the Dallas Cowboys and another nibble from the Seattle Seahawks.

The family's attorney, Michael Mitchell, said Settles reminded him of a young O. J. Simpson on the football field. A national magazine, Mitchell said, predicted Settles would be the fastest back in the West "if he avoids injury."

"Well, he didn't," Mitchell said.

The FBI is investigating the case as it applies to federal civil rights statutes, but chief assistant U.S. attorney Alexander H. Williams said his office would defer for now to the county district attorney, who has far more state statutes which apply to the case. A spokesman for the district attorney said a decision on whether to prosecute any of the policemen would be made within 30 days.

Los Angeles police department spokesman Lt. Dan Cooke said officer Brown had once worked for the department but had been fired. The Signal Hill police department has declined comment on the case.

The $50 million damage claim, filed Thursday by Settles' parents, said, "It is our belief that he was strangled or choked to death in some manner . . . . "

Officer Brown and the Signal Hill police department have declined to comment on any of the charges.

Police said they had found Settles hanging in his cell and cut him down. But a juror at the inquest, automobile club coordinator Linda Scott, said testimony by pathologists indicated that Settles' injuries could have been caused either by hanging or a choke hold. "We didn't have any pictures of him hanging. We don't know if he was suspended off the floor. All we have is pictures of him on the floor," she said.

Once the Signal Hill city government rejects the Settles' claim, which Mayor William F. Mendenhall said it would do, the Settleses may file a civil wrongful death lawsuit. The attorneys said they would do so, mostly to try to help prevent similar incidents from happening in the future.

Yesterday, Settles' parents turned out to root for their son's former teammates as they played Brigham Young University. The team lost, 31 to 8, but Settles' father said, "I want to be here . . . . Ronnie would have wanted us to be here. We want to continue to support the team. We want to be part of it. This was his life."