A Ukrainian lawmaker who met with President Donald Trump’s top lawyer Michael Cohen during the transition is now the subject of a treason investigation, according to several reports.

Prosecutors accused Andrii Artemenko, a member of Ukraine’s parliament, of conspiring with Russia to commit “subversive acts against Ukraine,” according to a Tuesday report by the New York Times. They accused Artemenko of pushing a proposed deal that could “legitimize the temporary occupation” of the Crimean peninsula, which Russia annexed by force in 2014.

Per the report, Artemenko met with Trump’s personal lawyer Michael Cohen and Trump associate Felix Sater, a convicted felon and government informant, to discuss the plan in January.

Cohen agreed to personally deliver to the White House a sealed envelope containing the peace plan, the New York Times reported on Sunday.

Artemenko said that he knew his proposal would be controversial and expected it to anger the Ukrainian government, according to a Thursday report by CNN.

“That’s why I feel pressure, and for sure today I can see people accusing me,” he said as quoted by CNN. “And I see the prosecutor of Ukraine is trying to do something, to open a new case, to do an investigation about me.”

Artemenko said his plan would let Ukrainian voters decide in a referendum whether to lease Crimea to Russia for a term of 50 or 100 years, according to the New York Times.

This would give Trump’s administration a glide path to lift sanctions President Barack Obama’s administration imposed on Russia.