A Woodacre man arrested for leaving explosives in front of his estranged wife’s house is facing new charges that he told fellow inmates he would kill the woman after his release, Marin and Sonoma County law enforcement officials said. Mark VanMidde, 49, was declared mentally incompetent to stand trial during a hearing held by Judge Jamie Thistlethwaite on Wednesday in Santa Rosa. Mr. VanMidde’s fellow inmates told officials that Mr. VanMidde promised to kill his…