As soon as Camden County Assistant Prosecutor Christine Shaw asked about the boy, Tweedley, a father of three, choked back tears.
"He was sitting above his mother's head, stroking her hair," Tweedley said, noting that a bloody butcher knife was nearby. He scooped the boy up in his arms and raced out of the apartment.
It was the second time Tweedley had been called to testify against Whye, who is charged with fatally stabbing Skinner after she broke off their relationship.
Whye was convicted of first-degree murder in 2010, but a three-judge Superior Court panel overturned the conviction, citing judicial error in instructing the jury.
Whye, who has a 10th-grade education, served as his own attorney during the first trial, assisted by lawyer Albert Afonso, a partner in Afonso, Baker & Archie in Cinnaminson.
Guided by Afonso, Whye asked to have jurors instructed that if they found him responsible for the death, they had the option to convict him of "passion provocation manslaughter" instead of first-degree murder.
If convicted of manslaughter, Whye faced significantly less time in prison. Superior Court Judge Samuel Natal ruled that because Whye did not argue passion provocation as a defense, it was an appropriate instruction. The appellate court disagreed and sent the case back for retrial.
Natal is also presiding over the second trial. Whye, who previously argued that he was not guilty and that there was no evidence linking him to the attack, is now represented by Brad Wertheimer of the Public Defender's Office.
In his opening statement, Wertheimer told the jurors they would hear terrible things and see graphic photos they would find very disturbing.
"We ask that you keep your minds open and put your emotions aside," Wertheimer said.
Two days after Skinner broke up with Whye, authorities allege, Whye confronted her at the apartment and stabbed her 30 times in front of their son.
Tweedley testified Wednesday that when he and Officer Corey Davis entered the apartment, Skinner was about five feet from the door, and her son, John, was near her head.
Tweedley recalled that as the boy held him and the two were face to face, John said: "Troy hit my face."
He took the boy, now being raised by relatives, to the apartment complex administrative office, where he was given a clean diaper, food, and toys. While playing and drawing, Tweedley said, the toddler would make stabbing gestures with a pen, repeat his father's name, make obscene remarks about women, and say, "Troy hit Mom-mom."
Tweedley said he tried to comfort the boy, talking to him as he had to his own three children when they were that age.
On cross-examination, Wertheimer noted how terrible the crime scene was.
Tweedley responded, "I've been an officer for 15 years, and this is the worst I've ever seen."
The trial continues Thursday.