A masked gunman cornered five teenagers in a field in 1996 and raped one of them, a murder jury has been told.
He indecently assaulted another and demanded money from them all, Swansea Crown Court heard.
John Cooper, 66, from Letterston, Pembrokeshire, denies rape, indecent assault and five attempted robberies at Swansea Crown Court.
He also denies murdering brother and sister Richard and Helen Thomas in 1985 and Peter and Gwenda Dixon in 1989.
The court heard that on the evening of 6 March 1996 the teenagers - three girls and two boys who cannot be identified for legal reasons - had been walking around fields and woodland near the Mount Estate School.
The jury watched police interviews with two of the girls - one who was 15 at the time and said was indecently assaulted and the other who was 16 and said she was raped.
The 15-year-old told police they were in a field walking home when they were approached by a man who shone a torch at them.
"He came up in front of us and was shining the torch in all our faces," she said in the police interview.
"He put the gun under the torch so we could see the barrel facing us. That's when everyone started to panic."
She told police the man demanded to know their names and ages and then forced them to lie face down on the ground.
He singled out the 16-year-old and separated her from the group.
Interviewed the following day she told police he pulled out a knife and forced her to remove one leg from her jeans.
"He put it [the knife] by my neck and told me to stop crying and not to tell anyone."
She said he was wearing a balaclava, a wax jacket and gloves.
She described him as smelling "dirty and musty". All the time he had the shotgun beside him.
"I just had so many things going through my mind... that he was going to kill me.
"He got off me, told me to get dressed and not to tell anyone."
She was in court with screens around her to protect her identity and watched the interview she gave to police 15 years ago.
It was put to her by defence barrister Mark Evans QC that the rape did not happen as she described.
But she told the jury how she described it in the video was how she remembered it.
The court heard the man then went back to the other teenagers who were still lying on the ground.
In the police interview the 15-year-old said he made her stand up.
She said he started touching her intimately, and was told: "If you tell anyone I will kill you, I know who you are."
She described him as wearing a sack over his head and thought he was accompanied by a dog.
He demanded money from all five of the teenagers but was told they did not have any.
The witnesses said as he walked away he fired the shotgun into the air.
Police were alerted as soon as the youngsters returned home.
It is the prosecution case that the man was Mr Cooper.
He is also accused of fatally shooting brother and sister Richard and Helen Thomas at their house at Scoveston Park, near Milford Haven, in 1985.
It is also alleged he shot holidaymakers Peter and Gwenda Dixon, from Oxfordshire, on the Pembrokeshire coast path in late June 1989.
Mr Cooper denies all charges and the trial continues.