By Mark Hosenball
WASHINGTON (Reuters) - U.S. investigators are trying to trace the contacts and movements in the United States of Chiheb Esseghaier, a Tunisian doctoral student in Canada who is one of two suspects arrested by Canadian authorities for allegedly plotting to derail a passenger train.
Sources close to the investigation said on Tuesday that Esseghaier, a Montreal resident, had made several trips to the United States. U.S. investigators are now trying to locate and check out people he might have met, the sources said.
One U.S. official said investigators were concerned that some of his contacts in the United States could be militants or extremists, although the source provided no details. Another official acknowledged that "loose ends" in the investigation were still being pursued in the United States.
Esseghaier and another man charged with an alleged al Qaeda-backed plot to derail a Canadian passenger train made their first court appearances on Tuesday, and the lawyer for one said his client would fight the charges vigorously.
They were arrested on Monday in separate raids after what police said was an investigation that started in the middle of last year after a tip from a member of the Muslim community.
Canadian police allege the plotters were contemplating blowing up a railway line that carried trains of Via Rail, Canada's national passenger railway service.
But U.S. officials said they believed that at some point, Esseghaier, 30, and his co-accused, Raed Jaser, 35, of Toronto, were contemplating using explosives to blow up a line that carried a daily Amtrak international train between Toronto and New York City.
The idea was to blow up a bridge or trestle before the train was about to pass over it, resulting in the train going off the rails, one U.S. official said. The official said the suspects had researched train routes and timetables.
U.S. and Canadian officials declined to comment on the record.
(Reporting by Mark Hosenball; Editing by Peter Cooney)