Montgomery County authorities investigate a death after responding to this house Tuesday on Great Elm Drive in Potomac. (Pete Piringer/Montgomery County Fire and Rescue Service)

On Monday, managers at the Bethesda-based Cystic Fibrosis Foundation had a meeting with one of their employees — technology specialist Andrew Racca. They told him that computer equipment was missing, that they suspected him of taking it and that they probably would have to call the police, law enforcement officials said.

Racca appeared nervous during the meeting. But certainly no one could have predicted what he would do the next day. And now, no one can explain it.

Sometime around 2 p.m. Tuesday, Racca drove to the Potomac home of an executive at the foundation.

The executive was not there. But his wife, Carolyn Mattingly, was. Racca killed her, drove off in his Mercedes-Benz and fatally shot himself, police said.

“Since the start of this investigation, there hasn’t been any evidence or indication of any association between Racca and Carolyn Mattingly,” said Capt. Paul Starks, a Montgomery County police spokesman.

Detectives were still awaiting final autopsy results before declaring how Mattingly died. There had a been a small fire in her garage, and she was burned.

“This is a senseless and tragic event,” Starks said. “There doesn’t appear to be any reason for her to have died.”

Friends of Mattingly, 57, who was a real estate agent and participated in a number of civic activities, remembered her fondly Wednesday.

One of her most passionate causes was organizing an annual conference for female prison inmates about to be released from the correctional facility in Jessup, Md.

“She was a diehard, totally committed to these women,” Prince George’s Circuit Court Judge Cathy Serrette said. “She was lovely — warm and very personable in a kind and generous way. . . . She was wonderful. We’re all heartbroken.”

The “Women Moving Forward” conference, organized through the National Association of Women Judges, provides all-day workshops on issues the women would soon have to tackle: Job interview skills, parenting and addiction problems, among others.

Serrette said Mattingly became involved in the program in 2008, when she served as chair of the Maryland Commission for Women, and remained active every year since, usually as treasurer of the event. Mattingly made a special point of making sure the women had new journals to write in, Serrette said.

Racca, 42, had been director of network operations for the f oundation since March, according to his Linked-In profile. Before that, according to the profile, he was a senior systems engineer at the foundation for about eight years.

His family members could not be reached for comment. And no one answered the door Wednesday afternoon at the red brick townhouse where he lived on Hillandale Road in Chevy Chase.

Mattingly’s husband, C. Richard Mattingly, is the chief operating officer of the nonprofit foundation. He has been involved in cystic fibrosis work for decades, having met a young girl with the disease while working as a college intern for the governor of Kentucky, according to a story on the foundation’s Web site. “I remember the innocence of the little girl that needed help,” he is quoted as saying.

Police said that managers at the foundation started talking to Racca about their concerns last Thursday. He did not show up for work Friday.

Supervisors at the foundation discovered the possible thefts during a recent audit, according to initial findings of the police investigation. The supervisors confronted Racca on Monday. He left the office, but did not make any dramatic gestures, Starks said.

There is no indication he had been fired or put on leave, Starks said.

The next day, Racca apparently slashed four tires of a car at the Mattinglys’ home before he killed Carolyn Mattingly, police said.

Police received a call at 1:13 p.m. for vandalism at the house, in the 12000 block of Great Elm Drive. Officers who responded spoke with Carolyn Mattingly, who said she had discovered the vandalism. She also said that her husband was at work.

Officers drove around the neighborhood, looking for suspicious people or vehicles but found neither, Starks said. The officers wrote a report and left the scene.

About 2:33 p.m., police received a call about a single car colliding into a tree off Piney Meetinghouse Road at River Road, authorities said. The driver turned out to be Racca. A handgun was found in the car.

At almost the same time, about 2:34 p.m., authorities received a call about a residential fire at the Mattingly home — about two miles away. Firefighters extinguished a small fire in the garage and found Carolyn Mattingly’s body inside.

H. Victoria Goldsborough, who knew Carolyn Mattingly from her work on the Maryland Commission for Women, described her friend as particularly interested in the Women of Tomorrow program, and frequently looked for ways to get younger women involved in their activities.

“We just had a vision to ensure that women were treated fairly and justly, especially our young ladies that were growing up, and that they would be able to see what they could do. . . . We used to share old stories about how we wanted to see things different from what it was when we were growing up.

“She was quiet in demeanor but strong,” Goldsborough said. “She was quiet, but she was not a pushover. You couldn’t take her meekness for weakness.”

“I know her husband’s devastated. I just know she just talked about him as the love of her life.”

In a statement, the Cystic Fibrosis Foundation said: “We are devastated by the tragic death of Carolyn Mattingly, the loving wife of the Cystic Fibrosis Foundation’s Executive Vice President and Chief Operating Officer, C. Richard Mattingly. . . . Our greatest concern is for the welfare of the Mattingly family, and we share our deepest sympathies with them during this extraordinarily difficult time.”