LONDON — A top counterterrorism detective was found guilty Thursday of trying to sell information to a Rupert Murdoch tabloid, becoming the first person to be convicted on charges related to Britain’s phone-hacking scandal since a police investigation was reopened in early 2011.

Detective Chief Inspector April Casburn was charged with misconduct for phoning the News of the World and offering to pass on information about whether London’s police force would reopen its stalled phone-hacking investigation.