Gloria Marmolejo was a loving mother who was very close to her family. When her son, David, started dating his underage stepsister, she obviously was very upset by this. She confronted her son and told him to change his ways but David wasn't ready to break up with stepsister.

Sources:

Twisted Love: Love is Relative Investigation Discovery

https://www.elpasotimes.com/story/archives/2020/02/19/david-marmolejo-past-marked-with-problems-law-family/4807193002/

https://casetext.com/case/marmolejo-v-state-16

https://www.azcentral.com/story/news/local/phoenix-breaking/2017/07/19/man-convicted-killing-mom-texas-faces-rape-charges-phoenix/490640001/

https://www.12news.com/article/news/local/valley/man-convicted-of-murdering-his-mother-pleads-guilty-to-raping-women-in-phoenix/75-463506340

https://thecinemaholic.com/gloria-marmolejo-murder-where-is-david-marmolejo-now/

https://kvia.com/news/2010/10/13/marmolejos-stepsister-ex-girlfriend-says-he-admitted-killing-mom-offers-details-of-murder-cleanup/

https://www.mysanantonio.com/news/local_news/article/S-A-jurors-to-decide-El-Paso-murder-case-1129277.php

https://www.victoriaadvocate.com/news/business/texas-man-gets-54-year-prison-term-in-moms-death/article_cdb3743c-8975-54a4-a2a6-4b7cfb8479a3.html

https://thecinemaholic.com/where-is-mariah-wilson-now/

https://www.newspapers.com/search/?query=David%20Marmolejo&p_province=us-tx&p_city=el%20paso