As police arrived at the motel, they found a female with a single gunshot wound to the chest.
She was taken to a local hospital then transferred to Methodist Hospital in Des Moines.
Captain Mike Hanken identifies the suspect as 31-year-old Jean Carlos Martinez Velazquez of Marshalltown.
He faces charges of attempted murder, aggravated domestic assault and methamphetamine-related charges.
The woman has not been identified yet and no condition report was released.
By Chuck Shockley, KFJB, Marshalltown