Halifax police have issued a warning to the municipality's residents about the release of a woman with a history of violent criminal convictions who is considered a high risk to reoffend.

Police say Melissa Ann Shepard was released from a federal women's jail in Truro, N.S., today after completing a sentence of just under three years for spiking her newlywed husband's coffee with tranquilizers.

Police note Shepard's other convictions -- including one for manslaughter -- date back to 1992, and her victims have included elderly men who were her intimate partners.

The 80-year-old, who is known as the "Black Widow," or "Internet Black Widow," has been assessed as a high risk to re-offend, and was denied parole last fall.

Earlier this week, Shepard agreed to abide by a number of conditions that include having her photo taken by police if she changes her appearance, a ban on using the internet, and not entering into any new romances without first informing police.

She is scheduled to appear in court on April 4 for a hearing on whether the conditions will be continued as part of a peace bond application.