A filmmaker had been documenting Joe Lieberman's life before he died.

Jonathan Gruber spent the past year working on a documentary about Lieberman.

Part of the documentary was filmed on Yale's campus with Lieberman this past summer.

Gruber had exclusive access to Lieberman, and says he even emailed him just a week ago.

Watch the full interview with Gruber in the video below:

Gruber told News 12 that Lieberman was not in poor health, so his sudden death was a shock.

The documentary is called "Centered."

Gruber says Lieberman was a remarkable man who was the same in public and his private life.

"He was caring and interested in who you were. I was grateful that he agreed to do the film. He was very humble about what was the purpose, you know why are we doing it, and I expressed as I did before in these polarizing times its someone who was a voice of moderation,” said Gruber.

Gruber went on to say Lieberman loved the Frank Sinatra song "My Way."

When he won his first Senate campaign against Lowell Weicker in 1988, he sang it to the audience.

Lieberman also sang it on the Conan O'Brien show when he was the vice presidential candidate.

The documentary will be released in May.