Mr Manning said the four female complainants were living in central Hawke's Bay at the time and had called 111 "looking for help", because of injury or illness.
"In particular [King] took advantage of his position as an ambulance officer. Who wouldn't trust a member of St John?
"[He] infused what would have been genuine medical touching with sexual touching."
A police investigation was launched after the youngest complainant, now 16, ran from an ambulance at the entrance to the Waipukurau Medical Centre on July 24 last year and claimed to have been sexually assaulted by King.
Mr Manning told the court the teenager was encouraged to breathe entonox, a pain relief gas, while on the way to the medical centre after King arrived at the girl's home following a domestic incident with her boyfriend.
After spending more than half an hour at the property, King, the sole officer attached to the ambulance, began driving towards Waipukurau before GPS tracker evidence indicates the ambulance stopped for 10 minutes near Waipawa, Mr Manning said.
"It was at this time she was sexually assaulted," he said. "The gas made her sleepy and disorientated ... he began touching her."
Mr Manning said the girl woke in the back of the ambulance, parked outside the medical centre, and found King kneeling next to her with his hands down her pants.
The Crown also alleges King recorded intimate videos of the teenage girl on his cell phone, however the former ambulance officer denies the claim. Mr Manning told the jury the Crown has "digital footprint" evidence showing King recorded the videos and later deleted them from his cell phone.
He said CCTV footage would also been presented to the jury showing the teen running from the ambulance into the arms of a delivery man before King emerged with his cell phone in hand.
All four complainants are expected to give evidence during the trial, which Judge Rea indicated would run until next week.
