By Olivia Lambert
It sounds like a real life horror movie. Two college students with a blossoming relationship were studying at the University of Kentucky.
Chris Maier and Holly Dunn had their whole lives ahead of them but one evening turned into a nightmare that changed everything.
On August 29, 1997, the couple went to a party not too far from campus. They decided to go and sit by the railway tracks and drink a few beers and it was there they came face-to-face with a serial killer.
Holly is the killer's only known survivor and she's telling the story of her horrific attack 20 years on, airing on CBS program 48 Hours on Saturday night.
'I'm going to die'
Angel Maturino Reséndiz, known as the Railroad Killer, was crouched behind an electricity box when he saw the couple walking towards him.
He jumped out and asked for money, but being two poor college students, they had nothing to give him.
Holly told CBS the killer then shook Chris' backpack but there was nothing he wanted.
"He asked Chris to get on his hands and knees," she said as she recounted the 20-year-old horror.
"He went through his backpack and didn't find anything he wanted and I didn't realise it, but he was tying up Chris' hands with the backpack behind his back.
"He took my belt and tied my hands up behind my back with my belt and he pulled Chris from the tracks on the gravel onto the grass beside the tracks.
"In my head I was panicking and saying my last prayer, thinking 'I'm going to die'."
The killer ripped a shirt and gagged Holly and Chris, but she kept sticking her tongue out to stop him.
'We had split seconds'
In a previous episode of Live to Tell on CBS, Holly told of how her survival instincts kicked in.
"We had split seconds in where - our attacker would go back up to the tracks and we were down in the grass. And so, we could talk to each other, and ... Chris and I started strategising," she said.
"You know, saying 'OK, should I run? Can you get untied?'
"I really don't know how much time passed before our attacker came down carrying a rock ... and he came over and literally just dropped it on Chris' head."
Holly said she realised in that moment the attacker was going to rape her. She tried to fight him but he held a weapon to her neck and said he could kill her easily and stabbed her.
She stared at every scar, blemish and tattoo on his body and tried to rip off her fingernails and dig in the dirt so at least somebody knew she was there if anything happened.
She started speaking to the serial killer and asked him personal questions like whether he had friends or family. She also asked how she could help him and begged him not to hurt her. He then began hitting her and her breathing was so shallow, she thought she was dead.
'I realised he was gone'
Holly didn't know how much time had passed but when she regained consciousness, the killer was gone.
"I knew that I was injured. I knew that I was hurt. I don't think I knew what my injuries were. I realised that my mouth wasn't shutting right. And I was covered in blood."
She then got up and walked almost 200 metres.
A senior university student, Chad Goetz, saw Holly stumbling near campus about 1am and he picked her up and put her on his couch and called an ambulance. She kept telling him Chris was still out there.
She had a broken eye socket and jaw and was covered in bruises and cuts.
"I remember they weren't talking about Chris. And, eventually, I asked my dad, I just said 'Chris is dead, isn't he?' and my dad was like 'yes he is'."
'The railroad killer'
Reséndiz murdered a doctor in Houston 14 months after he attacked Chris and Holly.
She had blunt trauma to the head and stabs wounds. She also appeared to have been raped.
Texas ranger Drew Carter told CBS they had forensic evidence and fingerprints that eventually were linked to a suspect who lived near railway tracks.
Police chased leads as more murders were committed and they connected up to 15 murders and traced them to Reséndiz.
"The majority of his attacks were by surprise. Often the people were in bed asleep when he was getting 'em. So he's like the boogeyman coming into your house. He supports the fact that true evil does exist in this world," Mr Carter said.
Police tracked down Reséndiz's sister who helped authorities find him.
He surrendered on July 13 1999. He was convicted of murder and was executed through a lethal injection in 2006.
CNN reported his last words were: "I want to ask if it is in your heart to forgive me. You don't have to. I know I allowed the Devil to rule my life. I just ask you to forgive me and ask the Lord to forgive me for allowing the devil to deceive me. I thank God for having patience in me. I don't deserve to cause you pain. You do not deserve this. I deserve what I am getting."