If the log was manually truncated since the last full backup, then there is no way to recover anything from the log as the log chain has been broken by the manual truncate.
Please ask your colleague when was the last time that he truncated the log.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability