The responsibility to decide whether a homicide is justified or chargeable based on the available evidence rests with the prosecutor. The prosecutor also must decide whether there is sufficient evidence to convince a jury beyond a reasonable doubt that the accused committed the crime. In proper preparation of a case, the prosecutor will rely upon good police investigation. A persuasive body of evidence is particularly important in homicide cases, because the jury will often be reluctant to convict an accused for homicide unless the evidence is overwhelming, given the seriousness of the penalities. The evidence presented at the trial can be of two types: direct evidence, which includes a statement by a witness about what he/she saw or heard, and circumstantial evidence, which does not directly prove a fact but points to the existence of that fact. Direct evidence may also be an exhibit that establishes a fact. Although most legal authorities believe it is more difficult to convict with circumstantial evidence than with direct evidence, the author has found that jurors do not like to convict just because they have been told what happened by an eyewitness. Even eyewitness testimony is often viewed by jurors as subjective in that it involves interpretation and conclusion by the observer. Jurors tend to want circumstantial evidence that reinforces eyewitness testimony. Although it usually takes more circumstantial evidence than direct evidence to convince a jury of a defendant's guilt, it has been the author's experience that once a juror is convinced of a fact by circumstantial evidence, that conviction is unshakeable. Two case studies of homicide cases prosecuted by the author are presented to demonstrate how evidence is collected, interpreted, and used in homicide prosecutions. Fifteen references are included.