There was a woman whose mother died. When she was at the funeral she met a guy who she fell instantly in love with. Unfortunately she didn't get his name or address and spent the next two weeks searching for him. Eventually she became so desperate she hired a private detective, but to no avail. Three days later she kills her sister.
Nice ones! Like the vicar idea but she would probably find him via the church? Undertaker? Likewise? Brother-in-law - interesting but she would probably have known him (if she knew where her sister was). All a bit drastic - killing to find a man?