Posting could elevate severity of man's charges in killing

A Twitter posting by an Arizona man who was arrested on suspicion of killing his roommate during a struggle could elevate the severity of charges he could face.

Two days before the fatal shooting, 21-year-old Zachary Dale Penton posted a comment saying he needed to move out of the Gilbert home where he was living before he killed his roommates.

The comment creates an opening for prosecutors to argue that Sunday's killing of Daniel Garofalo was premeditated. That means they could charge Penton with first-degree murder and seek the death penalty.

Penton's attorney says his client's social media posts weren't intended to be taken literally and believes the evidence will show he was acting in self-defense.

Investigators were analyzing physical evidence to determine whether Penton's account is credible.