Forty-six years after teenage Marilyn Wallman disappeared while riding to the school bus stop, a reward for information into her death has been doubled to a record $500,000.

On March 21, 1972, the 14-year-old schoolgirl left her Mackay home 10 minutes before her two brothers. A few minutes later, following the same route, her brothers discovered her bike abandoned on the road, her school books scattered.

Marilyn Wallman went missing in 1972. The case remains unsolved. Credit:File photo

Two years later a bone fragment was found that, in 2001, was confirmed to belong to Marilyn.

A $250,000 reward was issued for information over Marilyn's murder, which on Tuesday Police Minister Steven Miles announced was doubled to Queensland record of $500,000.