I'm interested in your thoughts on the Jodine Serrin case

Jodine Serrin was murdered on 14 February 2007 in her flat under very mysterious circumstances although her murder was later solved in 2018, through genetic genealogy. She was mentally disabled and lived alone but was helped by her parents.
Her parents knocked on her front door but no one answered so they attempted to use their spare to gain entry into their daughter's flat but the chain was on the latch which they had to broke. After they got into her flat everything seemed normal. They called her name multiple times but she didn't responded. Than her father opened her bathroom door and saw nacked men on top of her. They assumed that they had interrupted a very intimate moment of their daughter and were very embarassed. They asked the man to get dressed and come out of the room. When nothing happened for a while, they entered the room again and found their daughter motionless in bed. She had been dead for at least ten hours. Her murderer had raped her and beat her to death and than had sex with her corpse.
At about the same time, a neighbor saw a man running out of the building and was surprised at how much of a hurry he was in. A sweater was later found half a mile away in bushes that could be attributed to the perpetrator. They also found sneakers in Jodine's apartment, which suggests that she must have known her murderer, since Jodine always asked her guests to take off their shoes when they visited her. Tea cups were also found in the sink, but I couldn't find any information about whether the perpetrator's DNA was on them.
Her parents thought they had identified a friend of hers as the murderer, but he then had an alibi.
Nothing happened in this case until David Mabrito voluntarily provided DNA at a police stop in January 2011 because his truck had similarities to a vehicle that had recently been used in a robbery with which he had nothing to do. David Mabrito was an unemployed handyman living in the garage of his ex-wife for the last years of his life, who had left him in 2006 because he had a drug relapse but they remained friends. He was addicted to crystal meth and spent most of his time surfing on the beach. His ex-wife reports that he was very nervous after giving his DNA, but she didn't think much of it. When she visited relatives with her son, he was allowed to sleep in the house and killed himself there with a drug overdose, a week after giving his DNA to the police. His family created a memorial page for him on Facebook where only good comments about him were found in the first few years. Nobody could imagine why he took his own life. His cousin wrote that he was the friendliest boy she had ever met. He has no history of domestic violence until the murder of Jodine Serrin, when he was already 37 and he had a son of whom he was very proud. Today his Facebook page is full of hate, which I think is a shame because I believe he was a victim of his circumstances, although what he did was obviously one of the most bestial crimes that a human being can commit.
The police later solved his case with genealogical research, with David Mabrito initially deemed an unlikely suspect since Jodine's killer was of Northern European origin according to his DNA profile, while Mabrito is an Italian name until they found out that Mabrito's grandfather was adopted by an Italian couple. They then took a DNA sample from Mabrito's son because the sample that was taken from him in 2011 has now been contaminated. His family couldn't believe that he had committed such an crime until the police showed them a photo of the sneakers that were found in Jodine's apartment, which his ex-wife clearly identified as his, which shocked her. She says that she is now at least relieved to finally know why her ex-husband took his own life, since she had no idea about his motives for 7 years. She has now become friends with Jodine's parents.
The police cannot properly reconstruct the events of the crime, but believe that David took drugs in the apartment and killed Jodine while intoxicated.

I just can't believe how a seemingly normal guy who was described as one of the kindest souls alive and always ready to help could commit such an atrocity without an previous history of violence and with a stable circle of friends. A few questions remain open:
1) How did Jodine meet her murderer if she had no internet connection and David lived in a completely different city? Jodine worked voluntarily in a psychiatric hospital, which also had a drug rehabilitation clinic. But there is no proof that David ever made a therapy there. Surely that would be noted in the files? She had a lot of friends and none of them knew David Mabrito.
2) Did he tried to molest her when he was high on drugs, she fought back and then he killed her? Why would a Christian woman even hang out with a guy who takes meth in her apartment? Her other friends are harmless other mentally disabled people.
3) Did he killed himself out of guilt or because he was afraid of getting caught?
4) Can meth turn you into a necrophiliac rapist or does it just lower your inhibitions?
5) Do you think this was his first murder?

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