Puerto Rico's legislature has begun an impeachment process against Gov. Ricardo Rossello after an investigation into leaked chat messages found crimes may have been committed during the conversations, a senior legislator said on Wednesday.

Rossello, a first-term governor for the U.S. territory, has resisted calls to step down over a scandal local media have dubbed "Rickyleaks." Media, including El Nuevo Dia newspaper, cited unnamed sources as saying his resignation was imminent.

"The impeachment process has started," said Johnny Mendez, speaker of Puerto Rico's House of Representatives and a member of Rossello's party who was targeted in the chats.

An independent panel of lawyers commissioned by Mendez to investigate the offensive messages found four felonies and one misdemeanor may have been committed during the Telegram message group chats, one of the lawyers, Luis Rodriguez-Rivera, said in an email.

The governor, who is serving in his first elected office, is weighing his political future after almost two weeks of protests demanding his resignation, his spokesman, Anthony Maceira, said in a text message.

"Whichever decision he makes will, as always, be communicated officially," Maceira said.