Granted my comment is months later from your watch/review but I didn't see it clarified in comments. The body Mike dug up in the desert was the "good samaritan" that found the truck driver that Don Salamanca killed. Nacho told Mike they buried him in the desert. The body is unrelated to the lady from the grief meetings (the coroner from Law & Order) but when she was telling Mike about how she lost her husband 8yrs ago she said "it's the not knowing that's killing me". Mike didn't want the family of the good samaritan to go through that, especially feeling it was his fault he was killed in the 1st place; so he went out there, found him and called the Tribal police so that his family could at least have his body recovered.