Pennsylvania State Police are urging residents to adopt a tradition of displaying a blue light in their home or office window during the holidays in memory of fallen officers.

"This is always a tough time of year for the survivors," said State Police Commissioner Frank E. Pawlowski.

He said "Project Blue Light" was developed by Concerns of Police Survivors, a Missouri-based nonprofit that began in 1984 and represents more than 15,000 families of officers killed in the line of duty.

Pawlowski said the idea for the project came from Dolly Craig, the mother-in-law of a Philadelphia police officer, who wrote to the group in 1988 and said she would be putting blue candles in her living room window to honor Officer Daniel Gleason, who was killed in the line of duty on June 5, 1986.

"The color blue is symbolic of peace," Pawlowski said. "By displaying blue lights, you will show that you support America's law enforcement officers and that you hope 2011 will be a year of peace."

Pawlowski said two years ago a story got back to him after he issued his annual news release about "Project Blue Light."

He said a woman who stopped each morning to check on her elderly mother in Downingtown was surprised to find her dressed and ready to go out.

The reason? She had heard about the initiative and wanted to purchase blue lights, Pawlowski said.

"That's good citizenship; instead of remaining in the warmth and comfort of her home, she wanted to help pay tribute . . .," Pawlowski said. "It was nice to hear that the message had resonated."

He said 93 members of the Pennsylvania State Police have been killed in the line of duty since the department's founding in 1905. The most recent death occurred on Jan. 13, 2010, when Trooper Paul G. Richey, 40, a father of two children, was shot and killed while responding to a domestic incident in Venango County.

Pawlowski said a holiday tree with blue lights and one star for each of the 93 members killed in the line of duty stands in the lobby of state police headquarters in Susquehanna Township, Dauphin County.

"When we say that our colleagues will never be forgotten, those aren't hollow words," he said.

For more information about the project, visit www.nationalcops.org or www.psp.state.pa.us.

Contact staff writer Kathleen Brady Shea at 610-696-3815 or kbrady@phillynews.com.