An international investigation has led to arrests of four animal-rights activists suspected of harassing researchers working at University of California campuses.

Agents of the Federal Bureau of Investigation seized two of the suspects on 19 February in Charlotte, North Carolina, and the other two in Oakland, California, the following day.

The four are suspects in two incidents: an alleged trespassing involving a researcher from the Berkeley campus in 2007 and a home invasion at the residence of a professor at the Santa Cruz campus in 2008. Federal authorities are continuing an investigation of firebomb attacks on homes of researchers from the Los Angeles and Santa Cruz campuses.