A Frederick County grand jury dismissed manslaughter, child abuse and reckless endangerment charges against a man whose 5-month-old baby died after being left in his car for several hours on a hot September day, the county state's attorney announced yesterday.

After a 31/2-hour session yesterday, the grand jury indicted Frederick County resident Ralph C. Brown Jr., 45, on one count of leaving a child unattended in a motor vehicle, State's Attorney Scott L. Rolle said. The misdemeanor charge carries a maximum penalty of 30 days in jail and a $500 fine.

The case has received enormous attention in Frederick, where Brown is well known as a member of county's social services advisory board and son-in-law of city Alderman William G. Hall.

"I've probably received more public input . . . than any case I've ever handled," Rolle said. "And it was, frankly, right down the middle."

Some people thought that it was a tragic mistake, others that Brown should get a lengthy prison term, Rolle said.

Rolle said that Brown was responsible on Thursdays for taking the baby, Isaiah, to day care and one of his older sons to North Frederick Elementary School and that Brown would later work at home in Spring Ridge, north of Frederick. Usually, Brown would drop off Isaiah before the older boy, but they were behind schedule Sept. 8 so he took the older boy to school first and then returned home, apparently forgetting Isaiah in the back seat of his Buick, Rolle said.

The temperature was 85 degrees outside. By the time Brown realized his mistake, the baby had been in the car for several hours, and the temperature inside the car was 125 degrees. As Brown went to the car to pick up his son from elementary school, he realized what he had done, Rolle said.

The grand jury listened to the ensuing 911 call, in which Brown frantically asked for help in saving his child.

"It's as difficult a thing to listen to as I've ever listened to," Rolle said.

The baby died soon after paramedics arrived. The medical examiner's report determined that the death was caused by hyperthermia and was accidental. The report noted that there were no signs that the baby had been neglected or abused, Rolle said.

"It's terrible," he said. "The grief this family must feel is indescribable."