I dont really think Freda was Mario Bava's "mentor",but I could be wrong.
There are reports that Mario Bava finished I Vampiri (after Freda walked away) and also directed part of Caltiki though.
Thus supposedly getting his first chance at directing.
"The low budgets and strict shooting schedules of Italian genre film often overwhelmed directors and crews, and Bava had proven himself able at picking up the pieces. He had done so on I Vampiri, when Freda, frustrated, had walked off the set, forcing Bava to finish the film in two days. Bava had also contributed to several films as second-unit or fill-in director. In 1960, he finally made his first lone, credited foray into directing at the age of 46, La Maschera del Demonio." (Ferdy on Films)
Raro's releases are mostly top notch.
Murder obsession is a typical later Freda film,his early films are totally different from his later work in terms of style imho.
I personally prefer his early works.
From 1970 on he only directed a few movies (some he walked away from).
He was about 60 in 1970 btw,must have been about 70 years old when he directed Murder Obsession.
Riccardo Freda - IMDb