A Colorado state court this week vacated a murder conviction after prosecutors agreed that newly developed medical evidence showed an infant’s death was caused by pneumonia rather than abusive shaking. The ruling came after the defendant had spent 27 years in prison, making it one of the most significant criminal-case developments of the week both for the length of incarceration involved and for the prosecution’s unusual decision to support setting the conviction aside.

The case is notable because it centers on a familiar but increasingly scrutinized feature of older homicide prosecutions: medical testimony presented as definitive at trial, only to be challenged years later by advances in science and changes in professional consensus.