I thought my link in reference to AESF was rather self explanatory would you not agree.
The repulsive Mark Dixie apparently had a history of suspected sexual assaults vs women. It's a pity the Australian authorities did not appear to notify their UK of their suspicions when they deported him.
I doubt being a drug user turned him into a sexual predator but most likely increased the severity of his actions. Fortunately the law did not allow him to use his drug use as a defence in relation to the act of murder.