Maximillian Olegovich Soloviev was four years old when he vanished from Belmont, Massachusetts on June 8, 2006. At the time he was about 3 feet 8 inches tall, 40 pounds, with sandy blonde hair and blue eyes; he primarily speaks Russian and may go by Max, Maksusha, or Maximka. Records note possible alternate spellings or last names including Sobolev, Solovyev, or Tyukhtyaev.

Investigators have considered travel to Russia or to Caribbean islands as possibilities, but no confirmed sightings or contacts have been verified, and photographs or detailed identifying information for the mother are scarce.

The case remains open and listed in NamUs as MP20522 and in NCMEC materials as poster number 1061765. Very little new information has emerged publicly since the initial documentation. If anyone knew Maximillian or Anna, or has verifiable information about his whereabouts after June 8, 2006, please come forward.