CENTENNIAL, Colo. - Eighteen-year-old Isabella Yun-Mi Guzman emailed her mother "you will pay" and later spit in her face on the day before she allegedly killed her mother by stabbing her 79 times in her face and neck in the bathroom of their Aurora home, according to court records.
An autopsy showed the mother, 47-year-old Yun-Mi Hoy, died after being stabbed repeatedly in the face and neck, according to an arrest affidavit obtained by 7NEWS.
The teen's stepfather, Ryan Hoy, said his wife was attacked as she went to take a shower in an upstairs bathroom on Wednesday night. The stepfather told police he was eating dinner downstairs when he heard a thumping sound upstairs and his wife calling his name.
The stepfather said he rushed upstairs and heard the shower running and tried to push his way through the closed bathroom door. He said he caught a glimpse of Isabella, who pushed the door shut with her back and locked it.
Ryan Hoy said he saw blood seeping from under the bathroom door and ran to get his cellphone and called 911, telling a call-taker that he believed his wife was being attacked, the affidavit said.
The stepfather rushed back to the bathroom with 911 still on the phone and heard his wife say "Jehovah," the affidavit said.
Then the bathroom door opened and Isabella walked out, holding a knife downward in her right hand, the stepfather said. He said Isabella never said a word and stared straight ahead as she walked past him and went downstairs.
Ryan Hoy said he looked into the bathroom and saw the naked body of his wife, covered in blood on the floor. Her throat had been slashed, he told police, and a baseball bat was lying under her body.
Following the 911 dispatcher's instructions, Ryan Hoy tried to open his wife's airway and perform CPR. But he later told police his wife's eyes were staring blankly and he thought she was already dead. She was pronounced dead at the scene.
The stepfather said Isabella Guzman took the knife and fled the home clad only in a pink athletic bra and turquoise shorts, the affidavit said. She was arrested Thursday afternoon by Aurora police at a parking garage 2851 S. Parker Road, near East Hampden Avenue.
Ryan Hoy said his stepdaughter had argued with her mother often since she was young and, when she was about 7 years old, she had been sent to live with her father, Robert Guzman, for a while.
The stepfather said Isabella had become more "threatening and disrespectful" to her mother recently, including yelling at her mom and spitting in her face on Tuesday. Yun-Mi Hoy was so frightened of her daughter she asked her husband to sleep in the bedroom with her, the stepfather told police.
Then on Wednesday morning Yun-Mi Hoy showed her husband an email her daughter sent her that said in effect "you will pay," Ryan Hoy told police.
This prompted the mother to call police later Wednesday and ask officers to come to the home because her daughter "had threatened to harm her," the affidavit said.
Officers responding to the domestic disturbance arrived at the home and spoke with the mother and daughter, cautioning Isabella that her mother could throw her out of the home for her behavior, Ryan Hoy told police.
The teen's father, Robert Guzman, told 7NEWS he had counseled his daughter at her mother's request just hours before the killing. He said Isabella's mother was concerned about her teenage rebelliousness and her need to respect her elders.
The stepfather said things appeared to have calmed down after the police visit and the teen stayed in her room for the rest of the evening.
On Friday morning, a judge ordered Isabella Guzman held without bond on investigation of first-degree murder.
Guzman had a bandage on her right wrist and was wearing an orange jail jumpsuit during the brief appearance in Arapahoe County court, our partners at The Denver Post reported. She is being held in the Arapahoe County Jail.
-- Suspected homicide evidence found at parking garage --
Officers detained the teen after someone called 911 about 11:30 a.m to report a "body" inside a car in the parking garage on South Parker Road. Arriving officers found the car, but no one was inside.
"They did find items in the car, however, that led them to believe these items were related to the earlier homicide," Aurora police spokesman Frank Fania said.
Police called in undercover officers to help search the garage and "additional items were found that were believed to be involved [in the homicide] as well," Fania said.
A police K-9 team joined the search.
"At one point, Guzman was seen by officers walking out of the garage. She was then detained and taken to headquarters," Fania said.
Glenn Petty, who works in a nearby office building, said his secretary drew his attention to a handler with a dog searching the parking lot outside.
Petty said he saw a man dressed like a motorcycle gang member, who turned out to be an undercover officer, walking into the parking garage as a young woman walked out. Petty said the man and the woman briefly spoke and then she turned and walked away into a parking lot.
The first undercover officer followed the woman and was soon joined by two other plain clothes officers as they surrounded the young woman, who was carrying a plastic shopping bag.
"Suddenly, all three officers pulled guns" and the woman sat down next to a bush on a raised parking lot median, Petty said.
"It was very smoothly and very professionally done," Petty said. "It gave me a good feeling about the Aurora Police Department."
-- Family 'heartbroken' by death --
Robert Guzman spoke to 7NEWS before his daughter's arrest. He said the family was stunned by the death of his ex-wife.
"We're heartbroken. Of course we're upset over the death of my ex-wife," Robert Guzman said.
The father said he went to talk with Isabella at his ex-wife's request about three hours before the killing at the home where Isabella lived with her mother.
The father indicated Isabella had been engaging in teen rebelliousness.
"I went to talk to her because her mother was worried and wanted me to talk to Isabella," Robert Guzman said. "So, I went to talk to Isabella and we sat down in the backyard looking at the trees and the animals and I started to talk to her about the respect that people should have for their parents. And I was trying to let her know that she should be obedient to her parents, not rebellious, that she should try to listen more and everything was going fine.
"In the conversation, I thought that I made progress, but obviously it didn't do nothing, because hours later, this thing happened," the father said.
"Isabella is a good kid, she's a good hearted," Robert Guzman said. "But I don't know what could've happened, honestly, to provoke this kind of reaction."
-- Facebook photos show teen in 'Hello Kitty' T-shirt --
If there's a murder suspect stereotype, Guzman doesn't look the part.
The teen -- who goes by the nickname "Isa" -- looks like a beauty queen or model in photos on her Facebook page.
Her page has a photo of a watermelon slice with the word "Love" carved into it. There's also a photo of her wearing a 'Hello Kitty' T-shirt and jeans standing in front of a rock band set from a singing competition last year.