They discussed the kids at school that always seemed a little off. Maybe they had a clinically short fuse. Or perhaps there was a clear lack of empathy on display.

Plenty of Redditors described people that seemed totally normal, law abiding, and even docile. They couldn't believe when they heard the news later in life that the person took a life.

Whatever their original impression of the person was, it often only took on the appearance of a red flag or a haunting normalcy with 20/20 hindsight.

Unfortunately, the true weight of those signals only became clear after it was already too late.

xXDarkCubeXx asked, "People who have studied with convicted killers, how were they like in school?"

A Classic Sign

"One kid was a neighborhood friend of mine growing up. Super weird, terrible home life, not at all intelligent. Hung out with him because I thought everyone deserved a chance."

"Stopped hanging out when we collected crawdads (crayfish) from the creek; I was excited to make a little terrarium for them and watch them."

"I went home to eat dinner, and by the time I went back to his house he had pulled all their heads off and stuck them on to different bodies. Some were still twitching."

"20 years later, he was convicted of double homicide and arson. Could've seen that coming."

"Just realized this isn't quite what you were asking, but hey there's my story lol"

-- Sketchy_Life_Choices

Being a Jerk Is One Thing...

"There was this guy who lived on my dorm floor during college who ended up murdering his wife when he found out she cheated on him."

"He was a douche."

"Plus he was super racist."

-- manbearbatman

Out of Nowhere

"Went to an all girl catholic school. It was small so you got to know most other students. There was a sweet quiet girl in the trade below me. A bit shy but overall personable and nice. Had a good sense of humor and friends."

"I think 6 years after high school she and her boyfriend just decided they wanted to try murdering someone, so she called her police friend to meet her for a hike in the middle of nowhere and they killed her."

"Very odd."

-- Appledarling

Crime of Passion

"My older brother sat next to a dude in homeroom every day for 4 years of high school."

"Years later, when I was going through the same school, that dude my brother sat next to was involved in a big plot where he was having an affair with a married woman and they conspired to kill the husband."

"Did him with a shovel, buried him in the woods behind the high school just off a path a lot of kids used to walk to get to/from school. We got locked down one afternoon when the dogs found the shallow grave after a kid cutting class saw a shoe or something emerging from the dirt."

"Anyway, my brother has always maintained this guy was totally normal. None of the classic killer traits. Friendly enough, good for a joke, had a couple of tight friends, and never did anything obviously sketchy."

-- Shappomattox

As Simple As That

"Knew a guy who threw a chunk of sidewalk off an overpass and killed a truck driver."

"One day he's in school. The next day not."

"'Hey...where's Bobby?'"

"'He killed a guy with a chunk of cement.'"

"'Oh'"

-- Gert_B_Frobe1

Had No Idea How Bad It Was

"Ran cross country practice same time as the girls team, this girl one day wasn't picked up by her parents after practice and I usually ended late. When i finished i saw her alone i was concerned. She confided in me her mother was a drunk and very cruel and abusive."

"She cried and hugged me (first time we had ever spoken) . My mother arrived and we gave her a ride home and she talked to me more after that."

"I developed a crush on her, then suddenly she stopped coming to school."

"Years later we saw her on the news for luring her mother to a abandoned trailer and murdering her with a kitchen knife. I feel bad every day that i didn't see the warning signs and help her."

-- CartographerOk7345

Skewed Priorities

"Sociopathic jerk who bullied everyone who was smaller than him. Went to jail for beating a man's face in, then ripping his eyeball out while he was alive."

"But it's okay, it was a small religious town, so everyone forgave him."

-- HTMyers

Again, a Surprise

"He was the last person I thought would be involved in moving drugs, let alone harming anyone."

"He had awesome SNES games. Like all of them, and came to my place regularly. Always laughing."

"Shot another kid dead on the sidewalk in a turf war."

"I didn't know him I guess."

-- mindfeces

A Love Too Intense?

"Quiet, personable, devoted to his girlfriend. Married her after high school and within a couple of years murdered her."

"It was sad because she was a sweetheart and there were no indications he was unstable."

-- EdgarStormcrow

Goofy, Yet Violent

"I went to elementary school for a year or so with the guy who killed Whitey Bulger in prison."

"We weren't close, but played at recess and stuff like that. He was kinda goofy and seemed like a good kid. He definitely was not a bully-type or someone who caused trouble."

-- woodenman22

Caught in the Cross Fire

"One of my teachers in my community college committed a double-murder-suicide. The victims were his teenage sons."

"All to get back at his wife as they went through a messy divorce. The school actually shut down for the rest of the week."

-- RunsWithDogs12

Local Infamy 

"Not quite a convicted killer but I just saw him in a news story for attempting to kill a prison officer (he's there for attempted terrorism), he was honestly one of the nicest dudes ever when we were in school. Always super friendly, easy to talk to, funny."

"It was quite a shock to see his face on the news."

-- dustnbonesss

(Drugs)

"Editor of the yearbook and school paper. In lots of clubs. She was also a cheerleader for a year or two. I was friends with her so my freshman year I show up way too many times in the yearbook. Haha."

"She went to college and got into drugs. Dropped out, moved to Cali and became a sex worker, got deeper into drugs, and in her and some other people tried to kill 2 people. They only succeeded in killing one. All over credit card fraud."

"But it's weird to think that we would always partner up for sharing hotel rooms when we would travel for FBLA. Never would have guessed what the girl jumping on the bed next to me would grow up to be."

-- Grandma_Howard

Family Business

"The sons (yes plural) of a local drug kingpin. They were the go to dealers in highschool for hard drugs. They ended up killing one of their customers thinking he was a snitch."

"Shot him with a crossbow, chopped him up, and failed to hide the body in an old mining town because they were too high."

"Ended up being caught on camera, dad and the oldest son are out of jail because of Covid, younger son got off because the other two confessed and took the fall."

"They are also suspects in no less than 6 unsolved drug related killings in the area."

-- Snakebiteloo

"Unremarkable"

"I was in one class with a dude who later carried out a terror attack. He was quiet and unremarkable."

-- goatcheese4eva

(Drugs, again)

"A kid i went to grade school slit two peoples throats and lit their bodies on fire."

"He used to sh** and pi** his pants all the way through grade 6/7. Other than that he was fairly normal, maybe a bit on the wild side and not good at school but the shitting the pants was weird."

-- mancan

The Marks of Trauma

"I went to school with this girl who got arrested for handcuffing her children to their bed at night. There mattresses were heavily soiled. She was odd and acted up behind closed doors I guess."

"She also lived most her life in foster care with multiple other children it's really sad. Lack of parental figure left a void she didn't know how to fill I guess."

-- swamptalk