The Judica-Cordiglia brothers
In the late 1950s and 1960s, two brothers from Turin claim to have intercepted dozens of transmissions of secret Soviet space launches, including those of cosmonauts who perished in space before Yuri Gagarin officially became the first man in space.
There are those who believe that somewhere in the vast blackness of space, about nine billion miles from the Sun, the first human is about to cross the boundary of our Solar System into interstellar space. His body, perfectly preserved, is frozen at -270 degrees C (-454 °F); his tiny capsule has been silently sailing away from the Earth at 18,000 mph (29,000km/h) for the last 45 years. He is the original lost cosmonaut, whose rocket went up and, instead of coming back down, just kept on going.
You can hear a couple of their recordings here. Naturally, there is quite a bit of skepticism about the brothers' exploits.