Shawn Katrina Mason had just purchased her first home, not far from the Manassas neighborhood where she spent her childhood, and she was beginning to create a new life for herself. Her job at a federal credit union in the District was offering advancement opportunities, and she was working toward an accounting degree.

But Mason, 22, didn't show up for work Thursday, and friends and relatives couldn't reach her. On Thursday afternoon, according to Manassas City police, Mason was found shot to death in a back bedroom of her new house on Tarra Lane.

The shooting was the first homicide in the small city since January 2002. Police have not named any suspects in the death. Mason's family members said yesterday that they were in shock, describing her as a soft-spoken, focused woman who cared deeply about her career and her 3-year-old son.

"She was just the sweetest person," said Mason's father, Jason Lee of Manassas. "Things were looking up for her. She was extremely focused and tenacious about everything in her life. She was happy."

Police said yesterday that Mason was shot once in the head and that her home didn't show signs of a struggle. According to search warrant affidavits, detectives believe that Mason was shot in a hallway and moved to the bedroom and that she died there Wednesday night. An autopsy is pending.

Authorities said they learned of Mason's death about 1 p.m. Thursday, when an acquaintance who said he'd become concerned when he couldn't reach her and wanted to check on her was spotted breaking a window to get into the house.