Peru on Wednesday will expel Lori Berenson, the only American to serve time for terrorism in the South American nation, after completing her 20-year sentence, authorities said. "She will go through immigration normally but she is departing as someone being expelled," an immigration official said. Berenson, a New Yorker who is now 46, was arrested in 1995 and convicted of cooperating with the MRTA, an armed leftist group which plotted to take over the legislature.