This week she was released after two years, nine months and 10 days in jail for spiking the coffee of a new partner, Fred Weeks, her neighbour in a quiet retirement community in Nova Scotia. According to court documents, she knocked on his door and told him she was lonely, and she'd heard he was lonely too.

The couple had a civil union ceremony in his living room, and although the marriage was reportedly never certified, they went off on honeymoon to Newfoundland. Prosecutors said Shepard gave Weeks heavy doses of sedatives during the journey, leaving him unable to distinguish between the reverse and drive gears in his car, and to start the vehicle when they were disembarking from a ferry.

The next day he needed a wheelchair, could not put on his shoes and did not know where his car keys were, the court heard. But it was not until he was hospitalised after falling out of bed that the drugs were found in his system and police realised something was wrong.
...
1977-1991: Serves prison sentences for more than 30 separate convictions for fraud
1992: Convicted of manslaughter over the death of her second husband, Gordon Stewart, who she drugged and ran over twice with a car - she is sentenced to six years in jail but gets parole in 1994
1994: Features in a National Film Board documentary, When Women Kill, about victims of domestic abuse who attack their partners
2002: Her third husband, Robert Friedrich, dies just over a year after the couple meet through an online dating site - no charges are brought against her
2005: Sentenced to five years in prison in Florida after pleading guilty to seven charges, including forgery and theft from Alex Strategos, who she had met online - Strategos, now 84, says she stole about $20,000 from him and believes she put drugs in his ice cream
2013: Jailed for two years, nine months and 10 days in Canada for spiking her new partner's coffee with sedatives

http://www.bbc.co.uk/news/magazine-35838340