This is a commonly asked question and the answer is one that varies dependant on the nature of the sexual relationship. In Scotland it is an offence for any person to engage in a sexual relationship with a person under 16 years of age, irrespective if it is consensual or not. In order to obtain evidence of such offences, the co-operation of the 13 year old child would be required both in terms of them talking about the sexual relationship and obtaining evidence by means of a medical examination.
If the situation involves a child who appears to be exploited by an older person, all efforts to investigate these situations will be made in the hope that co-operation can be achieved and evidence gathered.
Contact the Child protection unit (by dialling 101) for further help and advice. If you want to make a complaint of under age sex, then contact Police Scotland by dialling 101 in the first instance.
You will first speak to a uniformed officer who will ask you/ your child some general questions (you can ask to speak to an officer of a particular sex if that would be more comfortable for you).