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Byers' Beat: How police tracked down suspected killer of pregnant St. Peters woman

Amethyst Killian’s family reported her missing after Thanksgiving. Her body was later found 75 yards from her home
Credit: St. Charles County/ Killian's family

ST CHARLES, Mo. — The investigation into the murder of a pregnant young mother in St. Peters turned the term “good old-fashioned police work” on its side.

Without technology, St. Charles County Prosecutor Tim Lohmar said this case could have easily grown cold.

“In the absence of this technology, the only way we solve this crime is if he gets arrested again and we have a DNA profile to compare to,” Lohmar said. “But that’s how a lot of cold cases are solved around the country.

“It’s certainly not something we would have solved quickly, and then you’ve got the anxiety of the community wondering, ‘Is there a serial killer on the loose?’ But because of technology, not only did we solve the case but we also solved it in an amazingly short period of time.”

It began when 22-year-old Amethyst Killian’s family reported her missing after Thanksgiving.

According to the family, Killian was last seen walking to a nearby gas station at around 1 a.m. Thursday. The St. Peters Police Department said her family reported her missing at 8 p.m. after she didn't return home all day.

By noon the next day, police found her body lying in some woods near where she lived with her mother, stepfather, children and boyfriend.

She had been stabbed more than 20 times.

She left behind a 5-month-old boy, a 7-year-old girl and had recently learned she was pregnant with her third child.

RELATED: 'Targeted act of violence' | Man charged with murder of pregnant St. Charles County woman

Her cellphone was missing, but family members told police she used a texting app to communicate.

Investigators found the app, which contained the IP address of her phone and the phones she was communicating with as well as the text of her messages.

An IP address is essentially the fingerprint that identifies a digital device, which can lead investigators to the device that sent a message, or a picture or an email, you get the drift.

The IP address led investigators to Damion Delgado’s mother.

“It was the first time we had a name,” Lohmar said.

Most times, search warrants on cellphones also only lead to proof that two people communicated via text messages, but doesn’t actually show the content of those messages.

But this app did, Lohmar said.

“That was huge,” Lohmar said. “The advancement was the actual text app itself was a cloud-based application, so we were able to tell exactly what she was doing in the moments right before she lost her life.”

And they were able to tell what the man now charged with her murder was doing, too.

They had not met before and agreed to meet up for consensual sex, Lohmar said.

He told Killian he was stopping at a gas station to buy a particular item just hours before the killing – which Lohmar declined to identify.

That sent police to gas stations in the vicinity, searching for surveillance footage.

But they got even more.

They knew the approximate time frame in which the man said he would be buying the item, and, once they found him, the store was able to pull the receipt and the credit card number he used.

That number gave them the name of Damion Delgado’s bank, which then confirmed his identity.

Police also noticed Delgado had a distinct gait to his walk on the surveillance video, Lohmar said.

“It was the way he swung his arms when he walked,” Lohmar said.

Police pulled his driver’s license photo, which matched the man they saw in the surveillance video.

Police also saw a sedan drop Delgado off at the gas station and learned it was an Uber driver.

The rideshare company identified the driver, who told police he picked up Delgado and dropped him off at Hobo’s, the restaurant near the crime scene.

They also pulled surveillance footage from a business near the crime scene.

It showed a man wearing the same clothing as Delgado and swinging his arms with the same distinct walking away from the crime scene about 45 minutes after police believe Killian was stabbed to death.

When police moved to arrest Delgado, his mother told them he was in the hospital after trying to commit suicide.

They got a search warrant for his DNA, and compared it to blood found at the crime scene.

It came back so certain to Delgado that you would have to multiple the earth’s population by about 30 to find another person with the same profile, Lohmar said.

“Twenty years ago, if he took a cab, we’d never know that, the cameras wouldn’t have captured anything, there would be no text communications, our best bet would be to get something on a video, but without anything else, that wouldn’t be very helpful,” Lohmar said. “This is definitely a crime, had it occurred before the technology we have now was available, it wouldn’t be solved yet and may never get solved.”

But there’s still one question technology can’t answer when it comes to this crime. And neither could old-fashioned police work.

Why was she killed?

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