Acquiring his degree from Manuel L. Quezon (MLQ) University, SACP Mendoza began a fruitful career starting off as an attorney. He passed the Real Estate Brokers Examination (DTI-9th Placer) and the Master Plumber Board Examination (PRC- 5th Placer) He previously taught part-time at FEATI University in 1991-1997.

Concurrently, he is the Reviewing and Co-Chief Inquest prosecutor of the Office of the City Prosecutor, Caloocan City. He has many collaborative works with different authors, such as Revised Rules on Evidence, Understanding Bails and Penalties, and Understanding Inques.