Jenny Sor, 40, of Monterey Park, California, was shot and killed on January 19, 2010, while visiting a senior housing facility in the 200 block of North Chandler Avenue with her boyfriend, Wenwa Chao. The shooting occurred just before 8 p.m.; both Sor and Chao were pronounced dead at the scene.

Authorities quickly identified the suspect as Richard Vithya Tauch, 45, described as Sor’s ex-boyfriend. Investigators say Tauch followed Sor into the facility through a glass patio door and shot both victims multiple times before fleeing. Tauch held a permit to carry a firearm while working as a security guard and was arrested the following day, January 20, 2010, then booked for investigation of double murder and held in lieu of $1 million bail at the Monterey Park jail.

What information about Sor, Chao, or the events that evening could help explain how the suspect gained access to the facility or why the attack occurred?