Conversation so far:
How long did Harold Shipman's trial last?
Harold Shipman's trial took six days of deliberation.
What year did Harold Shipman go on trial?
Harold Shipman's trial began at Preston Crown Court on 5 October 1999.
What was Harold Shipman on trial for?
Harold Shipman was charged with 15 counts of murder by lethal injections of diamorphine, all between 1995 and 1998.
Did any of the victims families testify at Harold Shipman's trial?
Angela Woodruff, Kathleen Grundy's daughter, appeared as first witness. Other victims relatives gave their accounts as the trial progressed.

Question: How was he accused of committing these murders?
Self-contained rewrite: How was Harold Shipman accused of committing these murders?