A 59-year-old Chevy Chase man suffered a heart attack and died Sunday moments after security guards accused him of stealing a 75-cent packet of pencils from a department store at the Wheaton Plaza shopping mall.

Police said the death of Grayson B. Tabler, head librarian for the Food and Drug Administration's Bureau of Foods, was "natural" and is not under further investigation. However, Dr. John Ball, a deputy state medical examiner, said yesterday he has requested an autopsy on Tabler "in case this goes to court."

Kevin O'Connell, an attorney representing the dead man's wife, said his client thought she and her husband "were being robbed" when the plainclothes guards approached him and that the guards "leapt" on her husband.

Police spokesmen said there was no evidence that the guards acted improperly when they approached Tabler outside the Montgomery Ward store in Wheaton Mall, nor were there indications that the guards used physical force. "They didn't touch him," said police spokesman Phil Caswell.

Montgomery Ward spokesman Ken Darre in Chicago said the store believes the guards acted properly and plans no action against them.

Police said the incident began around 12:30 p.m. Sunday, when security guards inside the home improvement section of the store allegedly watched Tabler hide the pencils in his coat sleeve. Tabler walked away and joined his wife and both went from the store to the parking lot, where they were confronted by the guards, police said.

Darre said that Tabler and his wife "started yelling and swinging their arms, demanding to see county police officers" when he was accused of shoplifting.

Suddenly, Tabler clutched his chest and started to fall, police said.

"Within a space of five minutes he had collapsed and (was dying) in her arms," O'Connell said. A rescue unit rushed Tabler to Holy Cross Hospital, where he was pronounced dead at 1:55 p.m.

Tabler's wife told police that her husband had suffered a heart attack in 1964 and had received treatment for a heart condition as recently as one month ago. On Saturday, she told police, the couple had walked together in the mountains.

Tabler had been an employe of the FDA for 17 years and FDA official Charles Exley, in a memo to Tabler's colleagues yesterday, praised Tabler's "seemingly endless energy and dedication that he brought to his job."