Small crates, crematories and an unusual text: How authorities found a dog trainer was responsible for the deaths of 11 dogs

By Taylor Romine, CNN

(CNN) — Although Miko was just a little over a year old, the shepherd mix had already grown into his adult frame. He was tall enough that his nose could graze a treat bag on someone’s waist; his once oversized paws now fit his large-breed heritage.

In June of last year, Miko’s owner, Alexander Kostyukevich, sought training for the young dog from someone he’d found on Instagram. He decided to use Happy K9 Academy after a successful session with the owner, Kwong Chun Sit, also known as Tony.

But just days after leaving his dog in Sit’s care, Kostyukevich got a text message that would devastate any pet owner: Miko was dead.

The mysterious death of the young, healthy dog in Southern California would eventually lead investigators on a morbid and disturbing journey to crematories, pet disposal services and a cargo van that reeked of bleach and feces as they continued to uncover more deaths.

Sit, 54, and his girlfriend, Tingfeng Liu, 24, were convicted last week – Sit on multiple counts of felony animal cruelty and other charges related to the deaths of nearly a dozen dogs, and Liu on several charges related to her help in carrying out the cremations. Prosecutors with the Orange County District Attorney’s Office said Sit left the dogs in small crates in the back of a hot van, where they died of heatstroke, and then pretended to be their owners so he could get them cremated.

The couple is set to face punishment for the horrific deaths during sentencing on July 10. Sit could be sentenced to almost 14 years in prison, while Liu could be sentenced to four years, according to the district attorney.

While the families will see justice served in court, they still have to live without their beloved dogs – and live with the reality of how they died.

The last remnants of these pets’ short lives remain on the internet in the training videos sent to families featured on YouTube: friendly dogs, big and small, with pants that mimic a smile, as they abided by the guidance of a man who was supposed to be their caretaker.

An unimaginable text message leads an owner to call police

The dogs Kostyukevich saw on Happy K9 Academy’s Instagram page seemed happy and obedient. When he got a text from Sit on June 18, 2025, just three days after he left Miko in Sit’s care, it was a shock:

I’m so sorry to let you know that Miko passed away peacefully during the night while resting. There were no signs of pain or struggle, and it was truly unexpected. I am deeply saddened by this loss.

Out of respect, I will refund the full training fee and offer additional compensation. The body has been lovingly cremated, and I will keep the ashes safe for you until you’re ready.

Please know my thoughts are with you. If you need anything, I’m here for you.

The message was surprising coming from a trainer who had gained business from word of mouth. Sit’s company had more than 40 five-star Google reviews over his six years of business, with reviewers making comments such as “couldn’t be happier,” “truly cares for the dogs he trains” and “He never disappoints.”

Kostyukevich called Sit to get information on what happened, according to a court document outlining what information would be addressed at trial, known as a trial brief. His immediate concern was that Sit had sold Miko, the document said. But Sit hung up on him, and Kostyukevich decided to call Irvine police.

1 unusual death leads to the discovery of 10 more

Casey Pickett, an animal services officer for the Irvine Police Department, began investigating. She called Sit and found out another dog in his care, Ziggy, was also dead. They had been picked up by a service called Mobile Pet Cremations, Pickett learned, which paused their cremation once they heard from law enforcement.

However, an employee of the crematory informed Pickett that not only did they have Miko and Ziggy, but they had also picked up another dog from Sit just the week before. And that wasn’t all: The employee said they’d spoken to another pet cremation business and discovered Sit had dropped off another two dogs there — which now meant five dogs were dead.

After learning of the numerous dogs dropped off across the various services, Pickett went to Sit’s home in the suburbs of Orange County, according to the trial brief. Sit told her only two dogs had died in their sleep overnight and he was “just so sad.”

Pickett then asked about two other dogs who had been sent to cremation services. Sit then acknowledged it was four dogs who died.

“Sit stated that he went to sleep for the night and woke up this morning to discover that all 4 dogs had died,” the trial brief said. He used two different services, he told police, “because of the expensive cost of paying for cremation services,” the trial brief said.

After the investigation was complete, authorities found out the couple had retained cremation or disposal services for a total of 11 dogs across four different businesses.

Sit would later be convicted of 19 charges: 11 felony counts of animal cruelty, seven misdemeanor counts of attempting to destroy evidence and one misdemeanor count of destroying evidence.

What led to the deaths of all the dogs was “a tragedy and has left many dog owners with sadness and anger,” Sit’s attorney Kate Corrigan said in a statement. She added her client is “a long time dog trainer,” and testimony during the trial showed his history and ability in training dogs.

“The deaths of the dogs was unexpected and not the result of intentional acts by my client,” she said.

As police discover remains, search of Sit’s home reveals concerning situation

While one of the dogs was already cremated by the time the deaths were discovered, many of the owners and services were able to pause the cremations. One woman scheduled a viewing to say goodbye to her almost-3-year-old pit bull, his muscular, auburn body now lifeless. He was supposed to come home that day after three weeks of training.

A veterinarian was able to examine the remaining dogs and determined eight died of hyperthermia and heatstroke, and one died of “blunt force trauma to the head with acute spinal injury and spiral fracture to the leg,” the trial brief said.

While Pickett was initially at Sit’s home, she got permission to see Sit’s black Mercedes cargo van. She reported the overwhelming odor of “bleach mixed with the strong smell of feces,” the trial brief said.

Police came back the next day with a search warrant for his home and cars, where they found nine crates left loose in the back of the van and a portable air conditioner venting air through the side of the vehicle, the trial brief said. A bottle of bleach was found on the passenger-side floorboard.

As an investigator was at Sit’s apartment, a report came in about another dog that died, adding up into a seemingly impossible number for a business that, until this point, had received few complaints.

Liu, Sit’s girlfriend, helped in getting the dogs to the crematories, according to prosecutors. During a search of Liu’s Tesla, investigators found a trash bag, which contained a pink dog collar with the name “Luna,” according to the trial brief. They also found a receipt from an animal disposal company that read “1 DOG DROP OFF PAID $160.00.”

Liu was convicted on one felony count of accessory to a felony, one misdemeanor count of destruction of evidence and two misdemeanor counts of attempted destruction of evidence.

Liu’s attorney argued “she was not the decision-maker in this case.” Frederick Fascenelli said they felt there was reasonable doubt left in the prosecution’s argument as to whether she knew a felony had been committed, and whether she tried to help Sit avoid arrest.

“The evidence demonstrated that she was a young woman, in an unfamiliar country, far removed from the authority and control exercised by Mr. Sit, and that many of the actions attributed to her were performed at the direction of others rather than as part of any independent criminal plan,” Fascenelli said in a statement.

Although they were disappointed with the verdict, they respect the jury’s decision and are reviewing their options following the trial, he said.

A trusted dog trainer ultimately betrayed his clients

While Happy K9 Academy’s social media featured dogs following commands and clients applauding their work, the investigation by authorities showed a darker side to the company’s business practices.

In May 2025, a client took her 4-year-old Belgian Malinois named Max to Happy K9 Academy for three weeks of training, the trial brief said. Everything appeared to be going normally, and she received regular video updates of her pup.

But six days in, Sit messaged her that Max had a bloody wound on his leg. She decided to take him to the vet, but when she picked him up, she noticed Max was in the back of the van in a crate so small, he was unable to fully stand, the trial brief said. Max also smelled awful, could barely walk and had about nine to 10 wounds on his body, according to the document.

Several years earlier, in 2021, another client sent her two Malti-poos, Capo and Tropez, for a four-week training, the trial brief said.

The updates she received regularly at the beginning started to dwindle. When she requested a photo of the dogs, Sit sent one showing them in a small crate with no blanket or water. She decided she wanted to stop the training and pick them up. Inside Sit’s van, she saw “the entire van filled with dog crates stacked on top of each other,” with dogs panting heavily and no access to water, the trial brief said.

While Sit’s attorney argues the deaths were not the result of intentional acts, prosecutors in the trial brief said he knew what he was doing by storing the dogs in the back of a hot van, “knew his actions were negligent, and simply did not care.”

Their Yelp page holds its spot in online search results, but now reads “CLOSED – Updated June 2026.”

While the Google reviews hold the memories of past clients sharing the triumphs of training, one review, written about a year ago, is a stark reminder of what happened:

“my 8 month old puppy died while under the care of Tony Sit and ‘Happy K9 Academy’. She was 100% healthy and now, 5 days into her training, she is gone — along with a second boarded dog who mysteriously died the same night. PLEASE BEWARE.”

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