OAKLAND -- A woman found beaten to death outside a recreation center Saturday morning was identified by police Monday as Kimberly Robertson, 23, of Oakland.

A bicyclist found Robertson about 6:40 a.m. Saturday on the sidewalk in the 1900 block of Third Avenue, outside the playing field of the Francis Marion Smith Recreation Center.

She was pronounced dead at the scene. Police are not sure how long she was there before being discovered.

Investigators are trying to determine whether she was killed there or elsewhere and left outside the recreation center, formerly known as the Park Boulevard Recreation Center, which is near the Parkway Theater.

Sgt. Randy Brandwood said police are trying to trace her last whereabouts and don't have a motive yet. Police said she lived in another part of the city. No arrests have been made.

Police were told Robertson had moved to Oakland from Texas last September and was the mother of a 3-year-old daughter who was being cared for by relatives. She had been living in East Oakland, miles from where she was found near Lake Merritt.

The killing is Oakland's 26th homicide of the year. Last year at this time there were 25 homicides in Oakland.

Police and Crime Stoppers of Oakland are offering up to $10,000 in reward money for information leading to the arrest of the killer. Anyone with information may call police at 510-238-3821 or Crime Stoppers at 510-777-8572.