Waszkiewicz left the woman bleeding in the middle of the street. She died on June 8 of pneumonia.
"She was attacked, she was thrown to the ground and her handbag was snatched from her," prosecutor Kate Brunner said during Waszkiewicz's week-long trial for manslaughter and robbery charges. "She was small, on her own, vulnerable - an easy target for a man desperate for money."
Surveillance video later showed him stopping the car to dump the bag.
In court, Waszkiewicz said that he never attacked the 100-year-old widow and had found the bag in the street, the BBC reported. "I didn't rob no one and I didn't see her - if I did see her I would probably ask, 'Miss, is that your bag?' "
But Waszkiewicz did not have a good answer for what he did after he ditched the bag. He fled Derby and drove to his mother's house in London. He scoured his car. And he changed his appearance by lopping off his long hair.
But prosecutors said Waszkiewicz had left behind a piece of physical evidence: A fingerprint on a receipt found in the stolen bag. He was known to authorities because of previous convictions.
When authorities came for him, he was hiding under his mother's bed.
By the time of the arrest, Kaczan was already dead. During the trial, jurors saw some of the final photos of the victim - her neck in a brace, her eyes and arm swollen and marred by purple bruises.
Jurors deliberated for just two hours Wednesday before returning a guilty verdict. Prosecutors had spent the past week speaking about a life snuffed out.
After being freed from the labor camp at the end of World War II, Kaczan had found a happy life in Derby, a city of a quarter million people that is 125 miles northwest of London, prosecutors said.
She enjoyed going to church, having her hair done and attending lunches at the Polish center, followed by games of bingo.
But some painful scars from her past remained. She refused to celebrate her milestone 100th birthday because it was on the same day the Nazis sentenced her to death.
One of her final acts, prosecutors said, was to "pray for her attacker before she died."
On Thursday, Waszkiewicz was sentenced to 15 years in prison for manslaughter and seven years in prison for robbery. During sentencing, his attorney told the court that Waszkiewicz was "not a monster," according to the BBC.
But Judge Nicholas Dean interjected: "What he is is a cowardly, petty criminal. What he did was dangerous. What he did led to awful, awful consequences."
" . . . There is tragic irony in the fact that Mrs. Kaczan had survived the unimaginable horror of a Nazi concentration camp and slave labor, as well as imminent execution, only to meet her end because of the cowardly and sordid actions of a petty criminal and drug addict on the streets of Derby."