Yakima Police are still trying to identify a man whose body was found in a parking lot on North Front Street early Monday morning.   Police Captain Rod Light says "It's causing investigators a great deal of frustration not being able to identify the man because every day that  goes by it makes our job more difficult in tracking down individuals who may have been invovled in the murder, in an investigation the first day or two is critical."  The man suffered from head trauma , but it's not know if that was the cause of death. An autopsy will be held tomorrow morning at 10 o'clock.  Light describes the victim as a white man in his fifties, gray hair and gray beard.  He had no identification, although he did have jewelry on, so it appears robbery wasn't the motive.   This is the first homicide of the year in the city of Yakima.