Hi!
It is possible to detect semen traces in the vagina/ cervix for up to 3 days after
intercourseCauses of painful intercourse
Sexual intercourse - painful. DNA analysis can be done to determine whose semen it is. When there is an allegation of
sexualCauses of sexual dysfunction
Erection problems
Female sexual dysfunction
Sexual problems overview assault, the victim can choose to be subjected to an exam with collection of evidence. This then follows a chain of evidence procedure so that the evidence can be used in court. A negative finding does NOT prove that intercourse did not take place however, because many factors could cause a false negative exam.
Unfortunately, I don't think that there is anyway to prove that intercourse did NOT occur, unless you have a witness who can provide an alibi.
You will need to hire a good attorney who is experienced in sexual assault cases.
Good luck!
Dr B