Police are building a profile of a criminal with "intimate knowledge" of the Jewish community after more than £110,000 worth of religious items was stolen in a spate of robberies.
At least eight robberies have taken place within three months in and around Golders Green, north-west London.
Detective Sergeant Julie Henderson of Barnet CID said a man had been caught on CCTV on two separate occasions punching a pin number into a keypad at Golders Green Synagogue. She believes that the same man is behind each robbery and said police were analysing video footage and footprints found at the locations.
Golders Green Synagogue, in Dunstan Road, was the first to be hit on December 4 last year when the synagogue office was searched, but nothing was taken. The following month, on January 15, the suspect again used the code and searched the office, without taking anything. On January 22, the rear door of the Torah Vodaas school, on the same site as the synagogue, was forced open, but nothing was taken.
There was an attempted break-in at the United Synagogue's office in Finchley. A cleaner noticed damage to a window on March 3.
Or Yisroel Sadigur in Golders Green was targeted on March 16, when the suspect entered through a small window on the ground floor and forced entry to the Ark through two sets of locked doors. Two silver breastplates, three silver yadayim (pointers), and silver bells, valued at £100,000, were stolen.
The previous week, the suspect broke into the rabbi's house, next door to the shul, stealing items to the value of £10,000.
Police confirmed that Ohr Chodosh, in Temple Fortune was broken into on March 14 and 24 when an attempt was made to prise open the metal safe.
But Ari Davis, who founded the synagogue 10 years ago, said it has happened more than just twice.
"It has happened at least three times in the past 10 days," he said. "It is very unpleasant entering the shul and finding the inside of the bimah emptied."
DS Henderson said: "These items are quite distinctive and must be being sold on within the community. "
Mark Gardner, of the Community Security Trust, said: "We ask the community to remain vigilant and ensure that premises are properly locked."