On August 19, 2016, Anderson played
softball with Matt in the evening. The two later returned to the Ertl residence where they spoke until 4a.m. on August 20, after which Matt went to bed. At 2a.m., Alayna was put to bed by her mother, Kayla Ertl. At 8a.m., both parents discovered that Alayna, Anderson, and Matt's 2002
GMC Sierra were missing. The parents filed a missing persons report with the Meeker County Sheriff's office two hours later. Following the report, the sheriff's office canvassed the Watkins area without success. The BCA then joined the investigation, canvassed a larger area, and reviewed security camera footage from local businesses, none of which bore progress. An
amber alert was issued for Alayna at 1:30p.m. While searching, authorities traced the Sierra by tracking a cell phone that Matt left inside it. It was determined that Anderson was in
Todd County from 6:30a.m. until 9a.m., at which point the cell phone was turned off. Anderson was also spotted at a convenience store in
Browerville at 8:30a.m., seemingly alone. According to court documents, at roughly 2p.m. the Cass County Sheriff's office received a tip from a caller claiming to be Anderson's father. They reported that Anderson asked to use their family's cabin in
Motley, and then permitted authorities to search the area. Two pairs of officers responded. One pair went to the cabin and found the Sierra in a nearby ravine, court documents alleging that Anderson parked it there to conceal it. When they searched the cabin, they found a
20-gauge shotgun, appropriate ammunition, and a
suicide note. The other pair alongside a
K-9 followed footsteps outside the cabin that led into the woods. At 4:30p.m. Anderson was found standing knee-deep in a swamp with a cut on his left wrist. He was unarmed and did not resist arrest. When asked where Alayna was, he indicated he did not know and that he did not want to talk. When pressured further, he admitted that Alayna was in the swamp and led officers to her body at 6:02p.m. Alayna's body was found unclothed and submerged in water roughly away from Watkins. She was pronounced dead on scene, and Anderson was charged and booked into
Crow Wing County jail. Alayna's
autopsy revealed her cause of death was
strangulation and
blunt force trauma with evidence of
sexual assault. == Criminal proceedings ==