[4][5][6] In 2001 and 2019, Boulogne attempted to sue Delon for legal recognition of paternity but without success.
He made appearances in films directed by Philippe Garrel, including The Inner Scar, which he starred in with Nico, and The Secret Son, in which he was credited as Ari Päffgen.
[12] Boulogne was found dead in his Paris apartment on 20 May 2023, following a heroin overdose a month before.
[13] Shortly after his death was announced, his half-brother Anthony Delon paid tribute to him on Instagram, expressing his "great sadness".
[citation needed] Boulogne was portrayed by Sandor Funtek in the 2017 film Nico, 1988.