A Missouri man was executed on Tuesday, according to the state's Department of Corrections, even though the prosecutor's office that secured his murder conviction 21 years ago expressed doubts about the integrity of the case and the victim's family said he should be spared.

Marcellus Williams had always maintained that he had nothing to do with the stabbing death of a former St. Louis Post-Dispatch reporter. State and federal courts rejected numerous last-minute requests to halt the execution and review the case.