Prominent Ugandan opposition lawmaker Robert Kyagulanyi, who was charged with treason and temporarily detained, has left for the United States to seek medical treatment, his lawyer said.

Kyagulanyi, a popular musician known by his stage name Bobi Wine, was elected last year and has amassed a large following among youth electrified by his scathing criticism of President Yoweri Museveni, sometimes delivered in his songs.

“He is headed to Boston right now,” his lawyer, Robert Amsterdam, told Reuters on Saturday, adding that Kyagulanyi was also expected to travel to Washington D.C. during his stay.

Kyagulanyi, who has emerged as formidable threat to the president who has been in power for 32 years, was charged with treason over his alleged role in the stoning of Museveni’s in August. He has pleaded not guilty to the charges.

The lawmaker has said he was beaten up and tortured while in detention. Police say they are investigating this allegation.

Protests had erupted in the Ugandan capital on Friday after police detained Kyagulanyi at the international airport during a previous attempt to travel abroad for medical care.

Nicholas Opiyo, another lawyer for Kyagulanyi, had said overnight on Twitter that the lawmaker was “on a KLM flight out of Entebbe Airport.”

He posted a video of the lawmaker sat in a wheelchair and holding crutches being wheeled through what appeared to be the airport.

Museveni has won praise in the West for his support against militant Islam in the region, but many Ugandans regard the 73-year-old as out of touch with his people, nearly 80 percent of whom are under the age of 30.

Museveni, in power since 1986, has repeatedly been accused by his opponents of rights abuses and the widespread use of security forces to suppress opposition to his rule. He denies charges that his government is involved in rights violations.