A 45-year-old woman who was partially disabled by rheumatoid arthritis was found shot to death and her 10-year-old son fatally wounded in their burning Annandale home yesterday by Fairfax County firefighters.

Mary Louise Bartholomew of 8601 Queen Elizabeth Blvd. was shot in the temple area of her head, County police reported. Her son Eric died at 10:10 a.m. in the Fairfax Hospital emergency room of a bullet wound to the back of his head, according to a hospital spokeswoman.

Sgt. Ernest King Fairfax County homicide squad supervisor, said police are awaiting final autopsy and laboratory reports before determining if the deaths were a double homicide or a homicide and suicide. He provided few other details, however.

"A lot depends on distances, shots and powders," King explained. He said a handgun was found in one of the bedrooms, but would not say which one. Mrs. Bartholomew's body, which also suffered burns, was found on the floor of the master bedroom and the boy was found on a bed in an adjoining bedroom, police said.

Police said that they found no note indicating suicide and that there were no signs of a forced entry. The shots were fired sometime between 8 and 9 a.m. police said.

The husband and father of the victims, Navy Capt. James H. Bartholomew was at work when the discovery was made, according to neighbors. Bartholomew is an assistant commander for resource management in the Naval Intelligence Command and is a former staff member for the Assistant Secretary of Defense. he could not be reached for comment.

Two daughters, Ann, 21, and Patricia, 16, were also away from the home at the time, police said.

Fairfax fire officials said that the blaze, which began in Mrs. Bartholomew's bed, was confined to her bedroom but that it caused an estimated $15,000 to $20,000 in smoke and water damage to the upper floors of the split-level $68,000 home. They declined to disclose the cause of the fire.

A passing motorist, Newton James of 8524 Helen Terr., Annandale, said he stopped at the Bartholomew home when he saw smoke billowing from attic vents. He said he tried to alert occupants of the home by knocking on the front and side doors. The doors were unlocked, he said, but smoke prevented him from entering the house.

Robert Armstrong, who lives across the street from the Bartholomew home, said he noticed James trying to rouse the family and telephoned to report the fire. Fire officials said the call was received at 9:09 a.m. Armstrong said he then called Bartholomew at work to advise him of the fire.

According to neighbors, "Lou," as Mary Louise Bartholomew was known, was never seen outside her home in recent months because of what they described as a worsening case of rheumatoid arthritis that made it painful and difficult for her to walk.

She had recently undergone extensive treatment in an attempt to alleviate the ailment. One treatment caused her to lose some of her hair and it had to be discontinued, according to Marjorie Groleau of 4908 Magdalene Ct.

She was willing to try anything and everything," Groleau said.

"She was delightful, very happy, always in the best of spirits," said Mrs. Andrew Wolf of 8600 Queen Elizabeth Blvd., directly across the street from the Bartholomew home.

Both neighbors said they often held hour-long telephone conversations with Mrs. Bartholomew. "She did talk a lot on the telephone - I think because she was a little lonely," Wolf said.

Groleau discounted the possibility that Mrs. Bartholomew was depressed about her condition. "I never saw that side of her. She never used the word pain. She would make fun of her condition," she said.

Eric, who was to have entered the fifth grade at Canterbury Woods Elementary School, was described by neighborhood friends as quiet and bright.

Thirteen-year-old Greg Haubner said that the oldest Bartholomew daughter, 21-year-old Ann, was working at the Drug Fair at Ravensworth Shopping Center at the time of the shootings. Haubner said his mother went to get her at work. When she saw the house, she collapsed and had to be taken to a neighbor's home, Groleau said.

Many of the Bartholomews' neighbors in the Canterbury Woods subdivision recalled another tragedy five years ago when two children and their mother were killed in a natural-gas explosion in their home, which was diagonally across the street from the Bartholomew residence.