The trial was told the 40-year-old had a number of previous convictions including shoplifting, creating false identification documents and one offence of battery.
He denied both charges, saying he had found the green handbag in the middle of the road, picked it up, and disposed of it at a well-known fly-tipping area because there was no cash.
Waszkiewicz, of Hilary Road in Shepherd’s Bush, west London, will be sentenced at the same court on Thursday.
The woman who survived the war in Poland only to be killed in Britain
In June, just days after the 100-year-old’s death, The Telegraph’s Chief Reporter Robert Mendick and Joe Shute looked back at her extraordinary life and its tragic end.
Lying on her hospital death bed, Zofija Kaczan, a 100-year-old widow, prayed for the man who had mugged her as she walked to church.
Mrs Kaczan died on Wednesday, nine days after the attack that left her with a broken neck, prompting police to open a murder investigation.
Her final act of forgiveness, say friends and the priest who prayed with her at Royal Derby Hospital, was a typical act of kindness from the devout Catholic.
She had grown up in Poland before the war, but was snatched from the street by the Nazis and sent to a concentration camp to work. She was at one point sentenced to death, but somehow avoided execution.