I think, IF it at all had to do with the mistresses, it was a hitman, sent by one or the other. Maybe, what the killer seemed to show Liz, was a notice asking "Is it you, Mrs. Sergio Barraza?" or "Is it you, the d-i-l of Oscar Barraza?" or "Is it you?" showing her a photo of herself besides Sergio/Oscar. No mistaken identity, I believe. Maybe, Liz was an emphatic d-i-l to Sergio's mother and had persuaded her, not to put up with cheating, and with this she helped starting the filing for divorce. MOO