5 chilling details about Kathryn Sinkevitch's brutal crime

In December 2016, Kathryn Sinkevitch committed a gruesome murder in Maricopa, Arizona, by fatally shooting her former boyfriend, 31-year-old Michael Agerter, in his garage. The incident took place shortly after he came home from a court-mandated paternity test.

Sinkevitch, who met Agerter online in 2013, shared a tumultuous and violent relationship with him. The two moved in together, got a dog, and initially shared an intimate relationship.

However, their relationship deteriorated during Sinkevitch's 2016 pregnancy with a series of increasing confrontations and her resistance to Agerter's attempts to claim paternity of their newly born son. Agerter tried to claim paternity and visitation rights for their newborn baby, something Sinkevitch resisted vehemently.

The day he was supposed to take the test, she ambushed him, shooting him several times in a premeditated attack, videotaped in part on surveillance. Police found evidence of planning, including a fabricated alibi and attempts at covering her tracks. Sinkevitch was apprehended days later, convicted of first-degree murder in 2019, and sentenced to life without parole.

The case highlights the dangers that can arise from custody disputes. For more, see Oxygen’s Snapped Season 31, Episode 22, titled Kathryn Sinkevitch, which re-aired on September 1, 2025, at 11:15 p.m. ET on Oxygen.

Five horrifying facts regarding the brutal crime of Kathryn Sinkevitch

1) The deteriorating relationship and prior incidents

Snapped Season 31, episode 22 (Image via Unsplash/ @ Scott Rodgerson)

Michael Agerter and Kathryn Sinkevitch began dating in 2013 after meeting online. They shared adventures such as skydiving and later moved in together in Tempe, Arizona, adopting a dog named Darwin. By 2016, Sinkevitch was pregnant, but the relationship turned sour. Agerter reported physical abuse, including being headbutted and bitten, which required stitches.

He moved to Maricopa for his safety, about 30 miles away, and obtained a protection order against her in April 2016.

Sinkevitch accused him of cheating, even going so far as to claim he was involved with his own sister, and continued to harass him. Before the murder, someone tried to burn down Agerter's home by torching the garage and front doors, causing damage, though no one was charged. Agerter installed surveillance cameras for protection.

Their son was born in October 2016, but Kathryn Sinkevitch claimed Agerter was not the father, leading to legal battles over paternity and visitation, as per Oxygen.

2) The paternity test as a trigger

DNA Test confirmed Michael was the father (Image via Unsplash/ @ Mufid Majnun)

The murder happened on December 16, 2016, the same day Agerter completed a court-ordered DNA test to prove he was the father of their two-month-old son. Kathryn Sinkevitch was against Agerter gaining any rights to the child and had filed court papers denying his paternity.

Co-workers said she talked about how it would be easier if Agerter "wasn't around" and even asked about using another baby for the test.

She hired a private investigator to find Agerter's new address and searched it on Google Maps. Cell phone records showed her movements that day, with her phone going off the network around 1:30 pm, right before the shooting.

This timing suggests she acted to stop him from seeing the results and challenging her custody. The dispute over the child was a key factor in the case, as noted in court documents, according to Oxygen.

3) The ambush in the garage

Michael was shot three times (Image via Unsplash/ @ Jakob Rosen)

Agerter was driving home around 2:30 pm when he was attacked. He was on the phone with his sister, who heard him say "Holy sh*t!" followed by three gunshots. Neighbors reported hearing the shots and saw a white van speed away. Police found Agerter slumped in his running car, wearing sunglasses, with wounds to the head, neck, and upper body.

Three shell casings were on the floor, and a shoe print was found in the mud nearby. Surveillance video showed a hooded figure in black, carrying papers, running from the van to the garage as Agerter arrived, then fleeing after 11 seconds.

The attack was quick and targeted, described as execution-style. Deputies responded to a welfare check from Agerter's worried family and discovered the scene with shattered glass and blood, as per Oxygen.

4) The false alibi and borrowed van

Kathryn borrowed a van to attack Michael (Image via Unsplash/ @ Jason Leung)

Kathryn Sinkevitch claimed she was at work all day, but evidence showed otherwise. She borrowed a co-worker's white van, the same one seen at the scene. Workplace cameras captured her leaving at 12:33 pm in a hooded sweatshirt, with the van departing soon after. It returned at 3:19 pm. She used the co-worker's keycard to create an alibi.

Gunshot residue was found inside the van and on sweatshirts linked to her. Her work computer had searches on hiding phone locations. The co-worker, B.H., initially supported the story but later cooperated, making a recorded call where Kathryn Sinkevitch admitted authorities could not prove her involvement.

Cell data confirmed her phone was off during the crime. This planning suggests efforts to cover her tracks, according to Oxygen.

5) The arrest, trial, and life sentence

Kathryn Sinkevitch was sentenced to life in prison (Image via Unsplash/ @ Ethan Wilkinson)

Kathryn Sinkevitch was arrested on December 21, 2016, at a co-worker's home in Tempe. Police found paternity papers in her car matching those in the video, stolen license plates, and a bin of clothes, suggesting she planned to flee with the baby. Her trial started in April 2019 and lasted nine days.

Witnesses included Agerter's sister on the phone call and police on the scene. The jury convicted her of first-degree premeditated murder on May 7, 2019. On June 6, Judge Kevin White sentenced her to natural life without parole.

She appealed in 2020, challenging evidence such as the recorded call and flight instructions, but the Arizona Court of Appeals affirmed the conviction, citing overwhelming proof. The case ended with her in prison, as per AP News.

Stay tuned for more upcoming shows on Oxygen.

About the author

Arvind Singh covers anime and pop culture at Sportskeeda, with a knack for capturing the essence of entertainment through his words. Although he graduated with a BSc in Transportation Technology, his interest in pop culture was ingrained in him from a young age. Witnessing Michael Jackson’s live concert on TV at just 4 years old ignited a lifelong admiration for diverse music and storytelling.

Arvind’s experience includes over a year as an Anime Writer for Sportskeeda, alongside contributions to GameRant’s anime division. He also held a position as a UK Custom Export Executive at Aquatic Freights Pvt. Ltd before delving into the world of journalistic writing. He is dedicated to ethical and relevant reporting through his meticulous sourcing of facts, ensuring he only conveys accurate information devoid of any bias.

In his leisure time, Arvind enjoys listening to rock music, writing poetry, and playing adventure video games. He admires the charisma of icons like Shahrukh Khan, the eloquence of Matthew McConaughey, and the smooth yet powerful vocals of Chester Bennington. Writing is an integral part of his life, and when it comes to expressing his interest and putting a whole scene into words, he could do it all day.

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Edited by Sriparna Barui