Des Moines man gets life sentence for Sonic stabbing

Spencer Antowyn Pierce Sr., 56, of Des Moines was sentenced to life in prison on Wednesday for the stabbing death of a Sonic Drive-In employee in Johnston. 

Pierce had waited outside of the restaurant at 5350 Merle Hay Road on March 7, 2022, until employees Jermaine Whitaker Moses and Donald Schisler arrived. Evidence showed that Pierce, armed with a knife, followed the men into an employee-only area of Sonic without permission and assaulted Schisler, then stabbed Moses, 20. 

On Dec. 7, a jury convicted Pierce of all counts: first-degree murder, two counts of first-degree burglary, and going armed with intent.  

Pierce was sentenced to mandatory life in prison without parole for the murder, as well as two 25-year sentences for the burglary charges and five years for going armed with intent. The sentences will be served concurrently.  

In 2013, Pierce was convicted of first-degree murder and robbery for the shooting death of Steve Harmon in Des Moines. That conviction was overturned on appeal. 

The case was prosecuted by Assistant County Attorneys Kevin Bell and Michael Salvner, with assistance from Lindsay Morris. The Polk County Attorney’s Office thanks officers of the Johnston Police Department for their investigation.