[Will his pension be taken away?]
Depends on the charges that stick:
http://askthelawyer.federaltimes.com/2014/01/27/q-a-session-crime-conviction-effect-on-retirement-pension/
[Being convicted of a crime almost never jeopardizes a federal pension – the rare exception to this rule for federal civil servants is the list of crimes codified at 5 U.S.C § 8312. Those charges almost all relate to criminal disloyalty to the United States: espionage, treason, sabotage, insurrection against the United States, improper sharing or intentional loss of certain highly classified documents, and so on. There are occasional efforts by some Members of Congress to expand the sorts of convictions which could cause a retiree to lose their federal pension, although none of those proposals have been passed to date.]