'I'm a CSI who's seen the most horrific crime scenes and this one stays with me forever'

A crime scene investigator has opened up about the most horrific case she's worked, candidly admitting that it's never left her.

It's a job that truly isn't for the faint of heart, with CSIs having to come face to face with the most brutal of crime scenes. But of course, someone has to do it - and Sheryl ‘Mac’ McCollum is one of those people.

Working for a Metro Atlanta Police Department in the US, McCollum's job sees her attend crime scenes on all scales - ranging from car accidents to full-fledged homicides - and look for evidence. She then tries to connect the dots to prove what happened, and try to find who did it.

She's pretty much seen it all in her career, but there's one case that's stuck with her to this very day, and she spoke about it to LADbible as part of our Honesty Box series.

Sheryl ‘Mac’ McCollum spoke about how the Adamsville massacre in 1999 was the case that stayed with her (LADbible Stories)

The 1999 Adamsville massacre in Atlanta

Cyrano Marks, armed with a pistol, went to the home of his girlfriend, Deleane Briskey, after she tried to end their relationship and brutally opened fire on her, her four children and her sister.

All but one of the family members was murdered, with 11-year-old Santonio Lucas managing to survive the horrific ordeal.

It wasn't an easy escape, however.

The poor boy was dragged around the house by Marks as he fatally shot his mum, aunt and siblings, before he managed to break free and run into a closet. When Marks found him, he placed a pillow in front of his face and pulled the trigger.

When the weapon jammed, Marks stepped back, fiddled with the gun and fired again. The bullet went through Santonio's elbow, injuring him but not killing him.

This is when the little boy's survival instincts kicked in, and he played dead, not even realising when Marks turned the gun on himself and took his own life.

'I will think of that family forever'

Santonio played dead for eight hours before he plucked up the courage to run to his neighbour's house, where he reportedly told them: "Would you help me? My stepdaddy just killed my mom, my auntie and all my family."

Speaking to LADbible about the case, McCollum says: "That kinda case will stay with you, not just through your career, but I will think of that family forever. Because one thing that was so horrible, you know a lot of people in the media have police scanners.

"So that came out. And so the media rushed there and they were respectfully across the street, but they did put the house up and said the whole family has been murdered.

"And grandma was watching TV when breaking news came in. And so by the time we could find her, she was almost in full cardiac arrest."

Cyrano Marks killed his girlfriend, her sister and three of her four children (Larry W. Smith/Getty Images)

Elsewhere in the episode, McCollum also delves into the strangest piece of evidence she's ever come across that she 'couldn't stop thinking about'.

"It was a double homicide," she explains. "The female victim was completely nude. She had a small washcloth on her chest. She had multiple stab wounds and was dead right there in the living room.

"The man sitting on the sofa completely dressed, undershirt, shirt, belt, pants, underwear, socks, boots, the whole bit. He had multiple stab wounds, but he had an extension cord. The male end hanging out of the belt loop went all the way down inside of his pants, with the female end hanging out at the bottom.

Check out the full Honesty Box episode below:

"Well, I kept thinking, 'What is that extension cord about?' This is weird. I've got two people, they dated each other, they knew each other in this apartment that at one time they shared, they're both stabbed to death.

"But that extension cord, I just kept going back to it 'cause it was so odd. And finally the captain was like, 'Hey, do you not see two dead people here?' And I did. But that extension cord was just so odd.

"Never did figure out what it was about. It bugs me now."