McDonald's identical twin's DNA was held on a national database
Police caught a serial sex attacker in Renfrewshire because his identical twin brother's DNA was held on the national database, it has emerged.
Kevan McDonald, from Paisley, admitted raping a 17-year-old girl in the town in April and a 33-year-old woman on a cycle path near Elderslie in June.
The 33-year-old also admitted attacking two teenage girls with intent to rape in Renfrew in May and Paisley in June.
Sentence on McDonald was deferred at the High Court in Glasgow.
Judge Lord Turnbull ordered him to be detained at the State Hospital on an interim compulsion order.
The judge will determine at a further hearing next year whether McDonald should be detained without limit of time.
The Crown has also asked him to consider imposing a lifelong restriction order.
The court heard how martial arts expert McDonald carried out the attacks over a three-month period between April and June this year.
He admitted raping a 17-year-old schoolgirl in Paisley town centre on 3 April after pouncing while she walked home alone from a night out with friends.
McDonald admitted targeting his second victim, a 16-year-old, in Renfrew on 27 May as she walked home in the early hours of the morning.
He hid in bushes and grabbed her as she walked past, dragging her into a wooded area.
The court heard how the girl's screams attracted the attention of a passing taxi driver who went to her aid.
His third victim, an 18-year-old girl, screamed for help as he attacked her in the early hours of 16 June in Paisley's Cochrane Street.
McDonald ran off after her friends heard her screams and ran to her aid.
His fourth victim, a 33-year-old woman, was attacked when she asked McDonald for directions while cycling along the cycle path between Newton Terrace and Main Road, Elderslie, on the afternoon of 16 June.
The court heard how he punched her on the face, grabbed her by the throat, compressed her neck, pulled her into woods, tied her hands with her trousers, and raped her.
McDonald appeared at the High Court in Glasgow
The court was also told that McDonald had stolen a mobile phone and an Ipod from the 16-year-old victim and a camera and phone from the 33-year-old woman.
These items were recovered when his home was searched by police.
Prosecutor Kath Harper explained how McDonald had been caught using his brother's DNA.
He said: "The DNA profiles recovered in relation to the two rapes were found to match the profile of the accused's identical twin brother.
"Police enquiries with the brother led to the accused attending at Paisley Police Offiice."
McDonald was later examined by six psychiatrists who found that he was sane and fit to plead and was sane at the time of the offences.
His defence advocate, Joe Barr, said his client was "totally ashamed of his conduct" and accepted that he had caused his victims "terrible trauma".