(CNN) -- Anonymous bomb threats to Jewish institutions have spiked to about 140 incidents across the country since January, according to the Anti-Defamation League.
In the third month of continued threats to Jewish community centers, schools and institutions, there are very few answers.
It's unclear who's making the threats, why and what the state of the investigation is.
Some of the bomb threats are emailed. Some of them are phone calls from muffled and distorted voices. O
RelSci News & Alerts gets you: