Which of the following tests is done for vaginal cells collected for the investigation for rape?

Lugol's iodine test:- Lugol's iodine is applied on glans penis. If the person has done sexual intercourse, then a brown colour will occur due to reaction between Lugol's iodine and glycogen (present in vaginal epithelial cells, which get deposited on Glans penis during sexual intercourse). This test is positive up to 4th day of sexual intercourse