Cape Town - A serial rapist, described as a "monster lurking in the shadows", has been sentenced to five life terms and 120 years imprisonment for his four-year reign of terror, after he was convicted of 30 rapes, 27 kidnappings, assault and numerous robberies.Sikhangele Mki, 34, had pleaded guilty to the charges, with no other explanation other than that he had been under the influence of alcohol during the commission of most of the crimes.READ HERE: Brandy made me do it - Cape Town serial rapistHis victims were mostly under the age of 16. The youngest was only 11.On Thursday, Judge Patricia Goliath said the father of two had acted like a "monster lurking in the shadows, preying on vulnerable women and girls, attacking, raping and robbing them"."He exploited the vulnerability of his unsuspecting victims, overpowered them and derived pleasure in the degradation and pain inflicted on them," she said."The accused is a serial sexual predator. Even in the event of the remote possibility of rehabilitation, it is clear that he is a danger to society."Five-year investigationGoliath ordered that the sentences run concurrently.The State had sought 15 life sentences and an additional 110 years for the 12 aggravated robberies, six attempted aggravated robberies, three attempted robberies, two robberies, four assaults with intent to do grievous bodily harm, 27 kidnappings and 30 rapes.Mki was arrested in May 2016 after being linked to the attacks through forensic evidence following an extensive five-year police investigation.He preyed on women in Khayelitsha and Delft, where he lived, and would approach and threaten his victims before robbing them of their money and jewellery.Five people, suspected of being behind the spate of rapes before Mki's arrest, were killed in mob justice attacks.