The district attorney has dropped his criminal investigation into the crane collapse last November that killed five people, saying drugs and alcohol played no part in the accident. The announcement followed a coroner's report on the crash in which the crane plunged 16 floors in the financial district Nov. 28. The operator, Lonnie Boggess, of Tacoma, Wash., three ironworkers and a bus driver on the street died in the mass of twisted steel and 21 people were injured. The investigation initially probed Boggess' personal life. Published reports at the time said he twice tried to commit suicide and was a chronic alcoholic. The coroner's report said Boggess' blood-alcohol level was .04%. Under state law, twice that amount constitutes "driving under the influence" of alcohol. Chief Medical Examiner Boyd G. Stephens also ruled out the possibility of suicide. "Dr. Stephens and his staff could find no medical or physical disability on the part of the crane operator or the iron-working crew which contributed to the crane collapse," said a brief statement by Dist. Atty. Arlo Smith. "Moreover, the medical examiner's office, on the basis of evidence now available, ruled out the possibility of suicide or impairment by substance abuse as well."