A licensed vocational nurse arrested for starting a deadly fire in her office to postpone the due date of a work project last month made her first court appearance on Tuesday but did not enter a plea.

Misty Ann Weaver, 34, was charged with three counts of felony murder and one count of first-degree arson. The fire March 28 spread throughout the fifth floor of a six-story building near a busy 10-lane highway during the evening rush hour. Three people were killed and six were injured.

During the brief hearing Tuesday, prosecutor John Jocher said Weaver told authorities that on the day of the fire, she re-entered the building after 5 p.m. and went into her office's kitchen area, where she got a lighter.

"She went into a supply closet and set fire to a cardboard box she believed contained plastic tubing," Jocher said.

Weaver waited until the flames on the box rose 4 to 5 inches before leaving, Jocher said.

The nurse is being held in the Harris County Jail under $330,000 bond. She said little during the hearing but smiled to her family just before she was taken away.

Her attorney, Todd Dupont, said he will hire experts to go into the building and review investigators' conclusions.

Jocher earlier said Weaver confessed to authorities about what happened, but that he had not seen her videotaped statement, reported The Houston Chronicle.

Attempts to contact Weaver's home were not successful Sunday as her phone number was not listed in local directories.

According to authorities, Weaver started the fire because she neglected to finish an accreditation audit that was due to her boss, a plastic surgeon, and feared losing her job because of it.

Weaver thought starting a small fire would postpone the audit, investigators said.

Her employer, Dr. Robert Capriotti, told The Houston Chronicle that the mother of two had financial troubles, including filing for bankruptcy, but that her problems didn't seem "pressing." He said that she had no access to office funds.

Capriotti also said Weaver continued to work in his relocated office after the fire.

Click here to read The Houston Chronicle story

Agents of the federal Bureau of Alcohol, Tobacco and Firearms said that after the fire, Weaver was asked to return to the arson office to clear up discrepancies in her story, where she admitted to setting the blaze, reported the Chronicle.

Three firefighters were among the injured in the blaze near Highway 610.

Among those killed were Jeanette Hargrove, 52, a budding victims' rights activist planning to testify that week against a man charged with sexually assaulting a family member several years ago.

Marvin Wells Sr., 46, a local pastor, and Shana Ellis, 38, were also killed.

The Associated Press contributed to this report.