New Delhi, July 28 -- Julian Brown, a 1.7 million-strong Instagram influencer and budding inventor from metro Atlanta, has been missing for nearly two weeks following a cryptic and alarming social media posts that suggested he felt he was in danger.

Julian Brown rose to prominence for his groundbreaking invention called Plastoline-a device he claimed could convert plastic waste into usable fuels like gasoline, diesel, and jet fuel. The innovation caught the attention of environmentalists and tech enthusiasts alike.

Brown, who had been passionate about environmental issues since his teenage years, had launched a GoFundMe campaign titled "Plastic to Fuel - Together We Will Heal Earth" with a $1 million fundraising goal to bring his invent...