Donnell R. Petite, the second of three young men tried on charges of hurling rocks at passing cars from a Capital Beltway overpass in May, was convicted yesterday on 34 misdemeanor and eight felony counts.

Petite and two others were each charged with throwing large rocks at 25 cars, seriously injuring six people.

Destiny Morris, 16, the most severely injured, suffered a fractured skull and was in a coma for six weeks. She has undergone therapy, but will probably never fully recover, according to testimony.

Prince George's County Circuit Court Judge William Missouri immediately revoked Petite's bond, as he did after the conviction of John L. Burgess, who will be sentenced Monday.

Petite's sentencing is scheduled for Jan. 7.

"The truth is, these young men acted injudiciously on this particular night," said Missouri, who rendered his verdict after hearing from 36 prosecution witnesses in two days. "I am not saying that makes them the criminals of the century, but Mr. Petite is going to do some time."

Assistant State's Attorney John Smathers said Petite, 18, could be sentenced to more than 400 years in prison. But he said he will recommend 50-year sentences for both Petite and Burgess.

The third defendant, Maurice E. Ford, is scheduled to be tried beginning Feb. 25.

Maureen Lamasney, Petite's attorney, said she was not surprised by the judge's verdict. The defense called no witnesses.

But Lamasney, in her closing statement, argued that victims had failed to identify Petite.

She also argued that Petite was intoxicated and therefore unable to form criminal intent.

"He said his intent was never to hurt somebody," she told the judge. "He said he thought he was having fun. His mind was influenced by alcohol."

But Smathers said that Petite's actions argued otherwise. Alcohol, he said, "did not affect Petite's aim. Time after time, he threw rocks right into the windshield. It didn't affect his reflexes, because time after time, he dodged in and out of cars to retrieve rocks" on the beltway.

Smathers said the three men gathered rocks from beneath the overpass, hurled them at cars, collected the rocks that missed and threw them again. When angry motorists stopped and chased them, he said, "they ran onto the bridge and did it again."

"Having fun, to Donnell Petite, was hurting people or killing people," the prosecutor said.

In an unsuccessful request that Petite, of Oxon Hill, be allowed to remain free on bond, his attorney said he has no prior record, is working as a dishwasher and took an exam Saturday for his high school equivalency degree.

Missouri dismissed 22 of the counts against Petite and acquitted him of 34 more, including all charges of assault with intent to murder, the most serious ones he faced.

He found Petite guilty of 18 counts of assault and battery, 16 of destruction of property, seven of assault with intent to disable and one of assault with intent to maim.

Altogether, Petite was convicted of four more counts -- all of them misdemeanors -- than was Burgess. Smathers said the added convictions were because "we got a couple more people to testify."

Smathers also introduced into evidence Petite's statement to police after the May 27 rock-throwing incident, photographs of all vehicles damaged by the rock-throwing and nine of the rocks recovered.