The Colombian Liberal Party lawmaker Sigifredo Lopez, 48, has been arrested on suspicion of helping to plan the kidnapping of himself and 11 of his colleagues in April 2002.
Colombia Reports says the announcement was made on Wednesday by the Liberal Party leader Simon Gaviria who said that Lopez has been suspended from the party pending the outcome of an investigation.
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Lopez is being questioned in the capital Bogota on suspicion of murder, treachery and hostage-taking.
9News quotes a Bogota radio station as saying that information leading to his arrest came from computers seized when the military killed the FARC rebel group leader Alfonso Cano or 'El Cabezon' in Nov 2011.
It explains that Lopez was freed in 2009, while the 11 other MPs were executed by the rebels in 2007 in "circumstances that remain unclear."
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Colombians are "stunned" by Lopez' arrest, according to Associated Press, adding that the authorities have not mentioned a possible motive.
The news agency says that Lopez has always maintained he survived because he was at a different but nearby location when the rebels carried out the executions, and attributed his survival "to a miracle of God."
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