I admit I haven't seen the film, so I cannot vouch for its accuracy. I wouldn't worry that you cannot recall the incident: it was quite heavily-featured in the press, but I guess some things we repress due to the fact that they perturb us... or maybe you had other things to think about! Anyway...
From memory (my mother doesn't like to talk abt it either, b/c her friend was related to the Wales-King family) the incident revolved around the murders of husband and wife millionaires Margaret Mary Wales-King, 69, and husband, Paul Aloysius King, whose age I have forgotten.
Um sometime in April 2002, the couple were invited to the home of their youngest son, Matthew. They didn' come home from the engagement, and their Mercedes was found in a nearby park shortly afterwards. The bodies were found in Marysville or someplace, buried poorly.
So laterish it emerges that Matthew King drugged his parents with some kind of depressant and then allegedly (according to his testimony) hit them in the neck. His wife Maritza observed what had happened and lied to prosecutors to protect her family and young son, but later went to the police.
In the autopsy tho, it said that the couple died of asphyxiation. The Wales-King family allege that 1) Maritza could have saved the two by calling an ambulance, and that 2) she most probably strangled them, thus explaining the discrepancy between the statements and the autopsy.
Matthew got some exceedingly long sentence, but Maritza was charged with perjury (or something similar), which was later suspended. Matthew maintained that he killed his mother to assert his independence, etc. etc... (not exclusively for money.) Although I read somewhere (I think Wikipedia) that he had a very low IQ, so maybe that contributed in some way.
Anywho

On to lighter topics....