Animal rights charity, PETA, is offering a £1,000 reward in the hunt for those who poisoned, and killed, three dogs in a north London park.
Two bull lurchers and a springer spaniel died after swallowing poison in Fryent Country Park in Brent.
Ben Williamson from PETA said: "It is imperative that any community faced with the abuse of animals take measures to find the culprit or culprits and stop the violence. Animal abusers are a danger to everyone."
Lesley Hastings was walking her dogs at Fryent Country Park Way on Thursday evening. Two of them ate what she thought was mouldy bread. But it turned out to be poison. While she was at the vet with one dog, the other died at home.