While it’s never been officially proven, there is a interesting story behind truecrypt. It was allegedly written by one guy (Paul Le Rou) who was a programmer turned cartel boss/gun/drug runner.

But back to your question, truecrypt was professionally audited and deemed “secure”, some issues were found but none that were back doors or significant. Shortly after(might have even been during) the audit truecrypt deleted all old versions and posted a weird message telling people to use bitlocker.

After some time veracrypt picked up the torch and has continued developing what was truecrypt.