Why did Oscar Pistorius commit murder?

Oscar Pistorius acknowledged that he had shot his girlfriend Reeva Steenkamp. But the sportsperson underlined that he had shot her because he had mistaken her for an intruder.
Police officers try to determine why the sportsman really shot Reeva Steenkamp. They found steroids at the athlete’s home.
Since anabolic steroids have been found in Oscar’s bedroom, it would be possibly argued that anabolic steroids caused uncontrolled violent behavior in the sportsman. Anabolic steroids would be blamed for the murder.
Actually, you should understand that it is quite hardly to claim that steroids are responsible for aggression and violent behavior. Researches related to this issue are quite limited. According to results of several studies, users of steroids are predisposed to aggression, paranoia, jealousy, etc. It is claimed that those that apply anabolic steroids are more likely to be involved in crimes than those who have nothing to do with these drugs. But it is necessary to consider that steroids may just contribute to aggression. Just these medications alone can’t cause aggression. They turn out to be just factors that contribute into uncontrolled aggression. Other factors should be also present for appearing of aggression. Circumstances play great role in such situations. So, it is even impossible to define whether steroids cause aggression or certain circumstances. Violent cases should be viewed as a complex of steroid use and circumstances.
It is also claimed by scientists that high testosterone levels are linked with aggression in several persons. So, it is important to note here that while certain persons with elevated testosterone levels experience aggression, others with high levels of testosterone are not predisposed to uncontrolled violence. This effect differs from one person to another.
You can note that the connection between application of steroids and crimes is a complicated issue. Specialists have not studied this condition well enough to implicate it. So, if defense lawyers of the Olympic athlete want to argue that steroids have made their client to murder his girlfriend, they should comprehend that they are going to use controversial affirmations.