Names of NYPD officers Rafael Ramos, Wenjian Liu etched into DC monument

WASHINGTON, D.C. (WABC) -- Four months after they were killed, New York City police officers Rafael Ramos and Wenjian Liu became a permanent part of the National Law Enforcement Memorial in Washington, D.C.

Ramos and Liu were targeted and shot last December in a parked patrol car in Brooklyn.

On Tuesday, two engravers sandblasted the names onto marble panels along a circular path with four entrances guarded by bronze lions.

The engravers, Kirk Bockman and Jim Lee, have added names to the memorial every year since it was dedicated in 1991. The 20,538 names date as far back as 1791 and represent officers of municipal, state and federal law enforcement agencies killed in the line of duty.

Bockman and Lee said their work is more than just a job.

"It's remembrance, and it's wonderful that it's here for the survivors and the families," Bockman said.

The lions represent the protective role of law enforcement, according to operations assistant Debbie Catena. The male lions lean proactively over the memorial to watch over playing cubs, which Catena said symbolizes law enforcement's role during chaotic times.

On the opposite entrances, a pair of lionesses watch over sleeping cubs to symbolize law enforcement during times of peace.

Thousands of law enforcement professionals will pay their respects to fallen officers and survivors during National Police Week next month. Members of the Ramos and Liu families are expected to attend a candlelight vigil at the memorial on May 13.