The imposter called up the 80-year-old woman last Friday, saying she was a cousin and would like to bring her child for a visit, a police statement said.
That evening the 30-year-old arrived at the elderly woman's apartment doorstep in Herford, North Rhine-Westphalia with a young boy and a white dog.
Despite some misgivings, the woman allowed the trio into her home, where they spent the entire weekend together, the statement said.
But on Sunday evening the three left suddenly. On Monday the retiree realised that her pocketbook had gone missing.
“Under the pretence of an appointment that had to be kept, the woman and her child left the retiree relatively suddenly on Sunday evening,” the statement said.
In addition to a “rather large sum” of cash, the woman's credit cards and identification card had been stolen.
Herford officers are now looking for a woman aged approximately 30-years-old, 175 centimetres tall, with short, dark hair. Her alleged son is believed to be about eight-years-old.