Staff at kosher shops barely batted an eyelid when a charity collector arrived to empty their tzedekah boxes.
The religious-looking man in black hat and beard visited shops and restaurants all over north-west London, nodding to onlookers as he politely helped himself to donations.
But now several have complained and have urged others to be on the lookout — because none of the charities involved have ever heard of him.
And one of the largest charities has even threatened not to replace the collection box unless they can be guaranteed it will not happen again.
It is unclear whether the culprit is a member of the Orthodox community — or someone posing as a religious man.
But his appearance has allowed him to enter the shops unchallenged and simply help himself.
At least two kosher businesses have reported such thefts to police. One of them, UJIA, has also warned nearly 30 outlets to be on their guard.
A spokeswoman said: “We are dismayed to discover that contributions appear to have been stolen from our charity boxes.
“We have strict procedures in place as the public give generously to UJIA and in good faith.
“If we are not satisfied with the response to an incident we will not replace the charity box.
“It is very unfortunate that an individual would choose to steal from the public and from charity.”
A manager at Mendy’s kosher superstore in Edgware said: “Someone did come in the other day. We believe he was an Israeli. He definitely looked religious. He took money from all the boxes.
“Some of the charities are quite upset. We now have a picture of him up in our window.”
Jacques Marciano, owner of White Fish in Hendon, said: “It was one guy and he had a beard and a hat. I was not in when it happened. He took his time and emptied the boxes, one by one.”