Was it day care operator Tisha Lynn Morley? Prosecutors charged the 36-year-old woman with first-degree felony child-abuse homicide, and they say she shook the infant in frustration and slammed his head into a changing table at her home.
Or was it someone else?
Morley's defense attorneys argued at trial that it was Lincoln's own brother, then-3-year-old Boston, who inflicted the fatal wounds.
And after two weeks of testimony, a 2nd District jury is expected to begin deliberating the case on Tuesday morning after hearing more than five hours of closing arguments from attorneys Monday that stretched into the evening.
Branden Miles, the chief criminal deputy attorney for the Weber County attorney's office, urged the jurors Monday to follow the evidence in making their conclusion. He pointed to a cracked changing table that had Lincoln's vomit on a strap and he said the injuries could be explained by Morley grabbing the infant by his arms and slamming his head and body on the table.
"This case is every parent's worst nightmare," he said. "... These [infants] are the most fragile members of our society. They are completely defenseless."
Miles asked the jury to find Morley guilty of child-abuse homicide a charge that carries a possible penalty of up to life in prison.
In his closing argument, defense attorney Logan Bushell did not ask the jury to let Morley go scot-free. He asked them to find her guilty of a lesser charge of negligent homicide, a class A misdemeanor that is punishable by up to a year in jail.
"If that's your decision, she can live with that," Bushell said. "But to convict her of child-abuse homicide? There is reasonable doubt here."
Bushell said Morley "second-guesses herself every day," and he said finding her guilty of the lesser count will hold her accountable for her role in Lincoln's death.
The defense attorney argued that Morley made the "mistake" of leaving Lincoln with his brother and other toddlers while she was sanitizing toys in the basement of her in-home day care. It was then, the defense argued, that Boston kicked his little brother and slammed his head in a door.
Bushell said that this "ugly" and "heartbreaking" theory is not a result of creative lawyering to provide a defense to his client: Their defense was rooted in the testimony of a then-3-year-old girl who told investigators that she saw Boston inflict the fatal injuries. While her version of events didn't perfectly explain every injury, Bushell said police and prosecutors didn't do enough to explore her version of events. She was dismissed as a little girl with a big imagination, Bushell argued, because it didn't match the police's theory that Morley harmed Lincoln.
"That little girl saw something," Bushell argued. "[She] saw something happen."
Prosecutors argued that it would have been impossible for a child Boston's size to inflict such significant injuries on an infant. Miles said it adds insult to injury for Lincoln's parents to not only lose their child, but then to have their other son blamed for his brother's death.
At the beginning of the trial, Lincoln's mother, Alesha Penland, told the jury that although Lincoln was a small baby, he was healthy and good natured until Feb. 19, 2014. She had dropped her sons off at Morley's house at 7 a.m. that day the third day of Lincoln's stay there. The Penlands had used the day care before, from the time Boston was 3 months to 1 year old.
Alesha Penland said she remembered getting a call from her husband, Christopher Penland, shortly after 5 p.m. that day, telling her to come home quickly because something was wrong with Lincoln. She recalled the young family rushing to McKay Dee Hospital, where a CT scan showed that the boy had a severe skull fracture.
She boarded a medical helicopter with Lincoln to Primary Children's Hospital in Salt Lake City, she said, and then waited for her husband to arrive as doctors worked feverishly on her son.
Ultimately, an MRI showed that Lincoln had no brain activity, she testified, choking back tears.
She and her husband called their extended family together so they could say their last goodbyes, Alesha Penland told the jury.
On Feb. 27 at 5:30 p.m., they took their child off life support. He died at 2:30 p.m. on Feb. 28.
Morley, who has remained free on bail since charges were filed in 2014, did not testify at her trial.