As the case of the Long Island serial killer continues to unfold, more disturbing details about who Rex Heuermann really is are coming to light…

As we previously reported, after more than a decade of searching police were finally able to make an arrest in the case of the Gilgo Beach murders. Heuermann, a 59-year-old architect working out of Manhattan, was charged with three counts of first-degree murder in the deaths of Melissa Barthelemy, Megan Waterman, and Amber Costello after his arrest on Thursday. Obviously there may well be more murders he’s charged with before it’s all over…

Since then, an old friend of his has decided to speak out — and she’s got some seriously chilling details about the man she now thinks of as a real-life Dexter.

Speaking with DailyMail.com on Monday, interior designer Katherine Shepherd revealed she worked for Heuermann for five years, and spent three of those years working on his home. They even became friends! She said thinking back to her interactions with the architect has been keeping her awake at night — and we can’t blame her, she spent so much time with him.

Related: How A Pizza Crust Helped Police Solve The Gilgo Beach Murders!

He seemed like such a nice guy to her, just wanting to share parts of his life. He seemed to care for her a lot — so the interior designer said she never would have suspected her colleague as a murder suspect. She thought he was smart and friendly, and maybe a bit socially awkward — but never in a million years did she believe he was a serial killer. This is why she compares Heuermann to Showtime‘s serial killer:

“He’s just like Dexter. You’d never know if you met him. Dexter was also super normal and then he had that other side.”

It’s worth noting, though, that Dexter only killed criminals, not innocent women! So in a lot of ways he’s like Dexter’s adversaries. Shepherd revealed she didn’t even know about her old pal’s allegations until Saturday when an old boss sent her the shocking reports:

“I googled his name and, Jesus, there he was. There was this picture of my colleague that I remembered dearly. I then spent the next eight hours reading every article I could find. I was shocked. How could this be the same man? … I’m like shaking right now.”

Jeez, we can’t imagine what it feels like to make such a horrific discovery about an old friend. So, so awful.

Her friendly relationship with Heuermann ended only a couple years before the alleged Gilgo Beach killings are believed to have started — and if found guilty, it’s safe to say she may have dodged a bullet. Maybe even literally!

Katherine recalled one time in particular when she was measuring Heuermann’s home for some renovations in 2005. She revealed he got particularly skittish about her opening one specific room. As his wife Asa Ellerup was upstairs washing the dishes while the children played, things got awkward with the future accused murderer when they went down to the basement:

“In the basement, there was this one room that was locked, and he said I couldn’t go into that room. I was like – ‘What the hell? That’s weird.’ And he was kind of joking, like, ‘Oh you can’t go in there because there’s things in there.'”

Sorry, WHAT?! So sus… but this was decades ago, before all the true crime shows. Besides, he gave her a reasonable excuse:

“And then he said, ‘I’ve got a bunch of guns.’ He was weird about it, and I was like ‘Okay, fine.’ I could measure around it.”

At the time, she dismissed the strange reaction he gave her, but after allegations against him came out, she began to wonder what was REALLY going on in that room:

“I didn’t understand why he was being so weird about it, and now I’m thinking, ‘What was he hiding?’ … It was a big room. What was happening in that room? Is that where he took the women?”

So scary to think about… There could have been all kinds of things going on in his super private “gun locker.” But also… it may have been a big gun locker, too! See, on a work trip to take a look at a firing range, Heuermann revealed guns were one of his hobbies, something she’d had no idea about:

“I met him out there and measured the gun range. And afterwards, he taught me how to fire a 9mm. I didn’t know he was so into guns, but here we were. He was telling me how to place my hands under the hammer so when the hammer went back it didn’t hit me. I fired like four or five shots and I hit the target, a picture of a beer bottle. It was pretty intense.”

Just how into guns was Heuermann?

On Sunday police entered his home, the same house he’s owned since 1994, and removed dozens of guns. Apparently he had 92 legally registered firearms! It’s unclear if he had any unregistered ones in addition, but he isn’t currently being charged for it if so. Not yet anyway. Investigators said most of these guns were rifles, and according to Suffolk County District Attorney Ray Tierney, they were kept locked in a huge safe. Police also found some other strange items in the home: including a child-sized doll kept in a glass display box. Ick!

The question is, was there more in the room than the gun safe?? Maybe we’ll learn one day. More and more is coming out about Heuermann now that he’s in police custody.

Katherine could use the info. While speaking to DM on Monday, she admitted she just can’t seem to wrap her head around the sweet man she once knew being an alleged serial killer. In the interview, she recalled going on work trips with him, sharing an office with him for two years, and even him taking her back to her apartment and giving her medicine when she slipped on some ice and got hurt.

She came into work anyway that day, despite having fallen. But she could barely stand later in the day. So her then-friend showed her kindness:

“Rex took me in a cab to urgent care, and waited for me while I got an MRI and everything else. And then he took me back to my apartment. My roommate was gone at the time. Rex got me settled into my room, and then he went off to get my medication. When he came back, he made sure I had something to eat and had my medication. And then he went home. He took care of me.”

These memories she has of Heuermann are all sour now, though, and she can’t bear to think about what could’ve happened to her if things were different back then:

“This is the same man that’s allegedly killing women, and he could have killed me right there in my apartment if he wanted to. No one was there. I’m not an ugly girl, but I guess I wasn’t on the menu, which is great. It’s all pretty surreal. I watch a lot of those crime shows and everything, but you never think in a million years it’s going to be you, or somebody you know.”

At the end of the interview, she still couldn’t contain her shock over the entire ordeal:

“How would I ever know a serial killer? What are the chances of that?”

Yeesh… what an awful way to catch up with an old friend… What do U think about Katherine’s connection with the alleged Long Island serial killer, Perezcious readers? Let us know (below).

[Image via Fox 5 New York/Showtime/YouTube/Suffolk County Sheriff]

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