By Nate Raymond
BOSTON (Reuters) - A Massachusetts man charged with plotting to attack police and behead a conservative blogger on behalf of Islamic State told someone online that he wanted to cause more harm than the 2013 Boston Marathon bombing, a prosecutor said on Wednesday.
David Wright's trial on charges of conspiring to help a foreign terrorist organization opened in Boston federal court with a prosecutor describing what she called his plan with two other men to kill Pamela Geller, a blogger who organized a 2015 "Draw Mohammed" contest in Texas.
"He stated in an online conversation that he wanted to harm the United States more than the Boston Marathon bombings, because in his words, that was not sufficient," Assistant U.S. Attorney Stephanie Siegmann told jurors.
A pair of ethnic Chechen brothers inspired by al Qaeda killed three people and injured more than 260 with a pair of homemade bombs in the 2013 Boston Marathon bombing.
Prosecutors said Wright, 27, plotted with his uncle, Usamaah Abdullah Rahim, and a third man, Nicholas Rovinski, to attempt to behead Geller in New York.
Law enforcement officers were monitoring their calls and, after hearing Rahim wanted to go after an "easier target" and attack police, attempted to question Rahim in a Boston supermarket parking lot, Siegmann said.
Rahim then brandished a knife and police shot him dead. The confrontation came after Wright on the call directed Rahim to carry out the execution, Siegmann said.
Rahim's family have denied he had shown any signs of radicalization. Wright and Rovinski were arrested after Rahim's death.
Defense lawyer Jessica Hedges said Wright had adopted the "tough-guy talk" of the Islamic State group after learning about them online, but that his interest was a "fantastical" one, and that he had no idea Rahim planned to actually confront police.
"This is not a referendum on ISIS," she said, using another name for Islamic State. "This case is about one young man and what he intended."
Geller organized the Garland, Texas, event in May 2015 to highlight cartoons of the Prophet Mohammad, images many Muslims consider blasphemous. Two gunmen attacked that event and were killed by police.
Rovinski has pleaded guilty to conspiring to provide material support to a terrorist organization.
Wright faces up to life in prison if convicted on charges including conspiracy to commit acts of terrorism transcending national boundaries, conspiracy to support a terrorist organization and obstruction of justice.
(Editing by Scott Malone and Jonathan Oatis)