Toby Gregory, 42, of Bland, faces a first-degree murder charge for killing his wife Thursday.
The Highway Patrol announced Gregory's arrest Friday afternoon - although he remains in police custody at Mercy Hospital, St. Louis, where he's being treated for an apparently self-inflicted gunshot wound.
His bond has been set at $500,000.
Gasconade County Prosecutor Mary Weston also charged Gregory with armed criminal action.
Patrol spokesman Scott White said Owensville Police Chief Robert Rickerd asked the Patrol's Division of Drug and Crime Control to help investigate the shooting death of Inez Gregory, 30, who was found dead Thursday evening outside her room at the Owensville Motor Inn.
Toby Gregory was found in the hotel's parking lot and taken to the St. Louis hospital for treatment of his wounds.
The Owensville police and Gasconade County sheriff's office also are part of the investigation, which White emphasized is ongoing.
An autopsy will be done Monday at University Hospital, Columbia, on Inez Gregory's body.
Online court records indicate Toby Gregory had filed for divorce on June 22 - and both Toby and Inez had appeared at a hearing Wednesday.
The docket entry on Case.net (courts.mo.gov) indicates the case was continued, but another hearing had not been scheduled.