Continuity mistake: When Jessica is having dinner, his glass swaps between full or almost empty depending on the shot.
Continuity mistake: When the episode begins, Jessica is having a meeting with Sally Wilson, who hangs a bag over her shoulder. A shot later, her bag is down and she is hanging it again.
Answer: In a flashback scene, it was shown that he had a violent temper, so it stands to reason that he finally killed her in a fit of rage.