 On some date between 15 May and 17 June 326 , Constantine had his eldest son Crispus , by <unk> , seized and put to death by " cold poison " at Pola ( Pula , Croatia ) . In July , Constantine had his wife , the Empress Fausta , killed at the behest of his mother , Helena . Fausta was left to die in an over @-@ heated bath . Their names were wiped from the face of many inscriptions , references to their lives in the literary record were erased , and the memory of both was condemned . Eusebius , for example , edited praise of Crispus out of later copies of his Historia Ecclesiastica , and his Vita Constantini contains no mention of Fausta or Crispus at all . Few ancient sources are willing to discuss possible motives for the events ; those few that do , offer unconvincing rationales , are of later provenance , and are generally unreliable . At the time of the executions , it was commonly believed that the Empress Fausta was either in an illicit relationship with Crispus , or was spreading rumors to that effect . A popular myth arose , modified to allude to Hippolytus – Phaedra legend , with the suggestion that Constantine killed Crispus and Fausta for their immoralities . One source , the largely fictional Passion of <unk> , probably penned in the eighth century by John of Damascus , makes the legendary connection explicit . As an interpretation of the executions , the myth rests on only " the slimmest of evidence " : sources that allude to the relationship between Crispus and Fausta are late and unreliable , and the modern suggestion that Constantine 's " godly " edicts of 326 and the irregularities of Crispus are somehow connected rests on no evidence at all . 
