Missing child: Mateo Rivera, 9, blue hoodie

I lost my nephew, Mateo Rivera, 9, this afternoon around 4:15pm near the Oneonta Public Library on Main Street. He was wearing a bright blue hoodie, gray sweatpants, and neon-yellow sneakers. He has a small crescent-shaped scar on his right eyebrow and wears a silver locket with our family initials on a thin chain, which he never takes off. We last saw him near the library steps behind the bookstore, heading toward Prospect Street and the SUNY Oneonta campus entrance. I'm really worried—he's shy and tends to wander, and he has a heart condition that needs monitoring, so please look out for him. If you spot him, please call or message me right away. Any help is appreciated.