Miller last made contact with her family on July 15 when she sent her mother a text message. According to the information used to charge Jason James Johnson with first-degree murder, police say that was also the day she was killed.
Johnson, 29, was arrested on Saturday at a Charlotte Lane address in Halifax and is also charged with indecently interfering with human remains.
The documents filed in Dartmouth provincial court allege the second offence happened in the Halifax Regional Municipality sometime between July 14 and Nov. 23.
There is no explanation about why Miller was in Hants County or why police believe her body was subsequently moved to Halifax. Her remains have not been found.
Halifax Regional Police have said Miller, who also goes by Catie, was in a relationship with Johnson.
She leaves behind a three-year-old son.