Sac County, IA (KICD) — The Sac County Sheriff has released new information about an investigation into a Wall Lake man who has been missing since November 21st.

David Schultz was supposed to deliver a semi of hogs that day, but the semi was found abandoned in the middle of Highway 20 in Sac County with the man’s wallet and cell phone still inside.

Over the weekend Sheriff Ken McClure issued a news release saying the area was immediately searched with a K-9 unit and an Iowa State Patrol plane armed with a heat sensor found nothing. Volunteers searched the area on foot and by drone for several more days.

Schultz was seen at the MM126 truck stop near Fort Dodge at 11:15 the evening of the 21st and his cell phone data confirms he arrived at the spot where his semi was found around 12:18am.

That day a person named David Schultz purchased a one-way airline ticket from Minneapolis to Phoenix, but airport surveillance shows it was NOT the David Schultz that is missing.

Sheriff McClure says the Iowa Department of Criminal Investigation continues to get search warrants to examine digital data that could help solve the case.