The Woodbury County Sheriff's Office isn't saying how an inmate died in his cell over the weekend.
32-year-old Thomas Huisman was booked on a charge of 2nd Degree Theft Thursday.
On Saturday he was found dead.
The Iowa Department of Criminal Investigation has taken over the investigation.
Agents don't suspect foul play, but will review security tapes and question jail staff and prisoners this week.
This is at least the second death at the county jail in recent months.
Another inmate died in his cell in March from an apparent medical problem.