This article originally appeared on Huffington Post.

My heart goes out to victims and their families of the massacre in Las Vegas. This tragedy has many of us wondering what could have been done to prevent it and why it happened. As a mental health and addiction expert, I am critically analyzing this situation in efforts to identify behavioral factors that may have contributed to this horrific event. Information recently released about medications prescribed to the gunman may serves as a small piece to this puzzle.

According to multiple sources, Stephen Paddock, a resident of Nevada, was the gunman who shot and killed 58 people and injured over 500 others at a country music concert in Las Vegas. And left countless other victims who will suffer from Post-Traumatic Stress Disorder (PTSD) for some time to come along from countless families, friends, workers who may experience Vicarious Trauma. Paddock was prescribed 50, 10 milligram diazepam tablets by his physician within the last month that we know of so far. According to John Hopkins Medical Center, the usual initial dose is 2mg/day. This tells us he either has been on this medication for a longer period of time, or he was started at an unusually high dose. Diazepam is known to potentially cause “agitation, severe depression and anger.” The physician provided instructions to Paddock to take one pill each day, although it is unclear if Paddock was taking them regularly or as prescribed. The autopsy report will hopefully provide evidence as to the amount in his system at the time of death.

What is diazepam for and what are the side effects?

Physicians prescribe diazepam for a variety of symptoms. Some of these include anxiety, alcohol withdrawal, seizures, and muscle spasms, according to RX Online. It is one of the many medications in the class of drugs called benzodiazepines. The prescription of benzodiazepines must only be done under careful consideration due to the extremely addictive nature of this class of drugs.

Diazepam can be paradoxical in nature due to the fact that the side effects can potentially mimic the condition the patient desires to relieve with the use of this medication. Additional side effects include drowsiness, dependence, confusion, insomnia, headaches, weakness, and anxiety. Trends have also been found indicating a relationship between the use of diazepam and an increase in anger. This rise in anger can be seen as outbursts, fits of rage, or seeming like the patient is looking to start a fight. This unique side effect of diazepam serves as one piece of the complex puzzle of Paddock’s actions in Las Vegas earlier this week.

How does diazepam work?

When used appropriately, diazepam boosts the effects of a neurotransmitter in the brain that works to balance levels of stress and anxiety. This neurotransmitter, called GABA, also has impact on motor control, vision, and other functions housed in the brain.

Details of the Incident

Police found a total of 47 guns between Paddock’s hotel room and two homes. Some of the firearms found in the hotel were high-powered rifles considered able to penetrate police armor. A significant amount of ammunition was also found upon the discovery of the firearms. Further inquiry to determine where Paddock purchased the materials resulted in talking with shop managers, who said Paddock purchased all of the materials legally and completed all necessary background checks and procedures. The shop manager also indicated Paddock did not show any signs of being unstable or unfit to own guns or ammunition.

Paddock’s girlfriend, Marilou Danley, was sent to the Philippines before the attack. Reporters have questioned her sisters, asking if Danley was aware of the plans for this attack or had any part in it. The sisters stated that Danley had no knowledge or expectation of this occurring and is probably very surprised as well. Danley flew back to the United States to participate in questioning about the attack, which her sisters say she will do cooperatively. The FBI in Los Angeles accompanied her for questioning.

What does all of this mean?

The information about the number of guns found in his room and homes along with the planned sending away of his girlfriend leaves interesting pieces of the puzzle to be considered. This, in addition to the details we have about his diazepam prescription, leave us with more information and still many unanswered questions. While we don’t if Paddock had an addiction to prescription pills or the motives behind these actions, it is important to consider his relationship with his medication(s), the quantity and frequency of his use when studying this event, and be aware of the dangerous side effects of benzodiazepines.