MISSOULA — Closing arguments in the W.R. Grace & Co. environmental crimes trial are under way in U.S. District Court in Missoula. Arguments by the prosecution got under way Wednesday morning and the defense was to present its closing in the afternoon. Assistant U.S. Attorney Kris McLean walked jurors through a series of memos and other documents that he said support government allegations against Grace and several former executives. They’re accused of conspiring to conceal dangers posed by asbestos in vermiculite mined at Libby years ago. Grace closed its Libby vermiculite mine in 1990. Some of the northwestern Montana community’s residents blame asbestos exposure for about 2,000 cases of illness and about 225 deaths. The trial began in February.