Police believe an Iowa City man killed his wife and four children, then tried to drown himself before dying in a fiery crash on I-80 Monday.

In a news conference Tuesday afternoon, investigators say they believe Steven Sueppel killed his wife, then tried to kill himself and his children in their garage by carbon monoxide poisoning. When that failed, he killed the children individually.

Iowa City Police Lt. Jim Steffen says investigators believe the children died by blunt force trauma, possibly from a baseball bat.

Steffen says that after the children died, Sueppel tried to drown himself in the Iowa River, then called 911 from a cell phone at 6:31 a.m. and calmly told police to "please go there immediately," referring to the family's home.

A few minutes later he crashed into the freeway abutment.

Police identified the children as 10-year-old Ethan, 8-year-old Seth 5-year-old Mira and 3-year-old Eleanor. Their bodies were found throughout the residence.

Wife Sheryl Sueppel was found dead in the master bedroom.

Steven Sueppel had been indicted last month for stealing more than a half-million dollars from the bank where he worked.

He was charged with one count of embezzlement of bank funds and six counts of money laundering while serving as the vice president and controller of Hills Bank and Trust. Authorities said the alleged thefts occurred between July 26, 2000 and September 12, 2007.

The 42-year-old Sueppel pleaded not guilty and was released on $250,000 bail. His trial was scheduled for April 21st.

A funeral for all six family members will be held Saturday in Iowa City.