Police say they discovered a swastika spray-painted on a Newtown synagogue this weekend.

Officers doing patrols around the area say they found the symbol on the side of Congregation Adath Israel Saturday morning. Detectives say the incident is a serious hate crime.

The Anti-Defamation League is offering $2,500 to anyone who comes forward with information.

Steve Ginsburg, from the ADL, says a strengthened relationship between houses of worship and law enforcement can help with protection from these crimes.

Police have added presence outside temples in response. Some temples have hired private security, according to the ADL.

The ADL says it encourages threat drills at least once a year, including lockdowns and evacuations. They say hate groups may try to probe a synagogue's security before an actual attack.

Ginsburg says the modes of protection depend on the community. "Our synagogues and houses of worship can't become armed fortresses," he says.