BILL CRIDER'S POP CULTURE MAGAZINE
This story rings a bell. Didn't it happen in England in the 1980s? A Soviet agent stabbed a political enemy with poison-tipped umbrella and the victim died.
Yes, this is a very similar event.
The case in England was a Soviet defector killed by the Bulgarian KGB. The umbrella the killer used injected the victim with a small pellet coated with ricin.