McKINNEY – Testimony in a Collin County courtroom Tuesday indicated that prosecutors believe a 14-month-old boy's nanny beat his head against a kitchen cabinet door, inflicting the severe brain damage that killed him in October.

During testimony on the second day of Ada Betty Cuadros Fernandez's capital murder trial, prosecutors connected exposed nail heads in a cracked cabinet door to bruises on Kyle Lazarchik's head.

Andra Lewis Krick, the prosecution's evidence analyst, said the nails in the cabinet door – taken from the Lazarchiks' kitchen and displayed in court – were the same distance apart as two small bruises on Kyle's right temple.

Ms. Cuadros Fernandez, Kyle's nanny, is accused of intentionally killing the boy, who died Oct. 15 after two days on life support. She has repeatedly denied purposely hurting Kyle.

"I never hurt that baby. Never," she said in an audio recording made by McKinney police investigators. She also said that she wished she were dead instead of Kyle.

"I want to switch with him," she said in the recording, played Tuesday in court. "I'm sorry ... because I bumped his head."

In that same interview on Oct. 13, Ms. Cuadros Fernandez, 28, told police that earlier that day, Kyle had started choking, vomiting and convulsing after eating lunch.

Ada Betty Cuadros Fernandez

Then, after police said they didn't believe her, she changed her story, saying she bumped Kyle's head on a door frame while carrying him to the playroom. Later she changed her account again to say that Kyle fell off the kitchen counter the night before.

Laurie Ewing, Ms. Cuadros Fernandez's attorney, called Kyle's death a tragic accident. She said he fell from the kitchen counter and hit his head again the next day.

But testimony given by Dr. Sheila Spotswood, a Dallas County medical examiner, paints a different picture.

As Collin County prosecutor Greg Davis displayed photographs of Kyle's autopsy on a large screen, Dr. Spotswood used a laser pointer to circle the overlapping bruising on Kyle's scalp and head. She described how Kyle's brain was swollen and bleeding, and his eyes were hemorrhaging.

Dr. Spotswood said the bruising pattern on his head shows that there were more than two impact sites and does not fit the defense's explanation.

"It would be two impacts with that ... [defense] scenario," Dr. Spotswood said. "And neither would be with very much force, not enough to cause injuries to the eyes or multiple bruises."

Causing the death of a child younger than 6 is considered capital murder and is punishable by life in prison or a death sentence.

Before Kyle was injured, Ms. Cuadros Fernandez, a native of Peru, had told the Lazarchiks that she planned to move home, but she agreed to stay to help them interview her replacement. She had a one-way plane ticket to leave on Oct. 29.

On the audio recording, Ms. Cuadros Fernandez told police that she cared for Kyle and his twin brother, Ryan, as if they were her children. She said that even though they are identical twins, she could tell them apart, especially based on their personalities.

Kyle "was the calmed-down one. He can be in one place all day long," Ms. Cuadros Fernandez said on the recording. "His brother is more active. ... But sometimes they switch."

Some of Ms. Cuadros Fernandez's family members have been at the trial both days, along with a handful of Spanish-language news agencies.

Testimony resumes Wednesday morning at the Collin County Courthouse in McKinney.

E-mail tellis@dallasnews.com