Nina Litvinova, a prominent ocean researcher and lifelong dissident, has died by suicide at age 80, leaving a final message that blamed the invasion of Ukraine and systemic domestic repression for her decision, one of her relatives said.

Litvinova’s body was found on Wednesday on a street in central Moscow. Law enforcement sources told the state-run RIA Novosti news agency that she left a suicide note.

Her cousin, journalist Maria Slonim, shared an excerpt of the note on Facebook. “We decided to show the real reason: she was killed by Putin,” Slonim wrote.

In the note, Litvinova wrote that life had become “unbearable” since the full-scale invasion of Ukraine.

“I tried to help them, but I’m exhausted, and I suffer day and night from helplessness,” Litvinova wrote, referring to those jailed in Russia for opposing the war. “I’m ashamed, but I gave up. Please forgive me.”