VINALHAVEN, Maine (AP) — Artist Robert Indiana, best known for his 1960s LOVE series, has died at his home in Maine. He was 89.

Indiana’s attorney says he died Saturday from respiratory failure.

Friends had expressed concern for his well-being because the reclusive artist hadn’t been heard from for some time. Kathleen Rogers, a friend and former publicist, says she was so concerned she recently contacted the Department of Health and Human Services to investigate. A DHHS spokeswoman didn’t immediately return a message.

Indiana is best known for his “LOVE” sculpture, in which the L and a leaning O sit atop the V and the E.

He’s also known for living a secluded life on Vinalhaven Island. In 2014, he disappointed fans by failing to make an appearance outside his home for an event dubbed International HOPE Day, which was inspired by his creativity.