We talked to Johnny's mother, Scarlett, who tells TMZ that Johnny and Tessa Farrell dated years ago and haven't stayed in touch ... not having spoken in at least 2-3 years. She says his family also hasn't maintained contact with her, which is why she's peeved about her comments.

Tessa's emotional plea for stricter laws in L.A. rings hollow for Scarlett, who tells us she believes Tessa is just clout-chasing -- even though Tessa's tearful video certainly seemed genuine. In fact, we spoke to her to get more detail about what she'd like to see change in L.A's criminal justice system.

Check it out ... Tessa says letting low-level crooks back onto the street under L.A.'s zero-bail policy is a recipe for disaster, and in this case, tragedy.

She reiterates her demand to swiftly catch the suspects responsible for killing Johnny -- and in the same breath, clarifies she was NOT sympathizing with them in her OG video.

You'll recall, in Tessa's viral clip, she tearfully spoke directly to the guy(s) who shot Johnny, saying she gets times are hard -- but noted they could just get a job instead of ripping off catalytic converters and murdering people ... a statement that rubbed some the wrong way.

In our follow-up interview, Tessa clarifies that committing crime, regardless of someone's circumstances, is never okay -- not equivocating one bit.

Still, it sounds like Wactor's family has soured on her, regardless. His mom says she wishes Tessa would stop using her son's name for press, while pointing out that some of the things Tessa has mentioned -- like the existence of surveillance video of the crime -- is news to her.

In terms of what happens next ... Scarlett says Johnny's body will be flown to South Carolina -- where his family lives -- and they'll have a memorial in L.A. for him at some point too.

Cops have yet to make an arrest, and we're hearing the murder has rattled many in law enforcement -- with sources telling us this is par for the course for the way criminals have been acting lately ... namely, more brazen and violent without provocation.

When it comes to catalytic converter thefts specifically ... our law enforcement sources say these have gotten more violent as of late, and we're told out-of-towners even flock to L.A. to pull this particular crime -- knowing if they get caught, they'll just get a slap on the wrist.