Alexandria Sheriff James H. Dunning was hospitalized Saturday suffering from severe dehydration and vertigo, a source close to the family said yesterday.

Dunning, 54, whose wife, Nancy, was found slain in their home nearly a year ago, was taken by family members to Inova Alexandria Hospital for treatment. It was unclear yesterday whether he remained hospitalized.

Dunning's family members had no comment.

Barbara Gordon, spokeswoman for the city of Alexandria, yesterday referred all questions on the sheriff's condition to Richard R. Ruscak, the undersheriff, who did not respond to telephone messages left at his home and office or to pages.

Nancy Dunning, 56, a fixture in her Del Ray neighborhood, was found shot to death Dec. 5, lying by the front door of her home on West Mount Ida Avenue.

Police have said that Nancy Dunning -- who earned the nickname "Queen of Del Ray" for her devotion to the neighborhood -- was not killed randomly but was targeted, motivated by an event or relationship in her past.

One theory investigators are pursuing is that someone was paid or recruited to kill her, according to law enforcement sources.

"It's an open, active investigation, and it remains a top priority," said Alexandria police spokeswoman Amy Bertsch.

In January, police sought the public's help in identifying a man they believe may still be a potential witness in the case.

Photographs of the man were taken by a surveillance camera at the Target store in the Potomac Yard shopping center in Alexandria.

Dunning and the man were shopping in the same area of the store and exited simultaneously at 10:30 a.m. the day she was killed.

An hour later, Nancy Dunning failed to show up for a scheduled lunch date at the Atlantis restaurant in the Bradlee shopping center with her husband and son, Chris Dunning.

Father and son returned home to find Nancy Dunning lying on the floor dead. Sources familiar with the investigation said there were no signs of forced entry.

A $100,000 reward fund, raised by friends and relatives, is being offered to help find the killer.

Elected sheriff in 1986, James Dunning is known nationwide for running a jail that is efficient and safe.

In the last four years, he has overseen some of the country's most high-profile inmates, including convicted spies Robert P. Hanssen and Brian P. Regan; John Walker Lindh, who was captured in Afghanistan with the Taliban; and terror suspect Zacarias Moussaoui, who is accused of conspiring in the Sept. 11, 2001, attacks.

Staff writer Elaine Rivera contributed to this report.

Alexandria Sheriff James H. Dunning was suffering from dehydration and vertigo, a family source said.