HOUSTON -- Police officers across Houston prepare to say goodbye to one of their colleagues as the search continues for his killer.

Funeral services for Officer Reuben De Leon, 30, will be held at Our Lady of Guadalupe Catholic Church, 514 Carlisle Street in Rosenberg, at 10 a.m. Saturday.

De Leon was fatally shot early Wednesday morning at the Woodscape Apartments on South Gessner Street near Bissonnet Street.

Investigators said De Leon was with a female officer inside an apartment unit used by security guards and police who patrol the area when the killer knocked on the door and shot him in the chest when he opened it.

A composite sketch of the suspect was released Wednesday afternoon.

Witnesses described the gunman to police as a black man between 25 and 30 years old with wavy hair. He's between 5 feet 8 and 5 feet 9 inches tall, weighing 180 to 190 pounds. The gunman had a scar or mark on his bottom lip, and he was wearing a black-and-white windbreaker.

Police consider the man armed and dangerous.

A $20,000 reward is being offered for information that leads to an arrest and conviction in this case.

Anyone with information should call the Houston Police Department's Homicide Division at (713) 308-3600 or Crime Stoppers at (713) 222-TIPS.