Baker said that he has no idea where the crushed pills came from and that he searched the Internet because he was trying to protect his wife, who he said was increasingly dependent on sleeping pills.
"I did research to see: Can you overdose? Is that even a possibility that I need to worry about, my wife overdosing on sleeping pills?" Baker said.
And he asked that if his wife's counselor really believed he would hurt her, why didn't the counselor do more to protect her?
"She [Kari Baker] never looked me in the face and said, 'I think you might hurt me,'" Matt Baker said.
In his 2008 interview, Baker seemed to contradict himself when discussing who found the suicide note.
On the phone with the 911 operator, he said he found the suicide note, but during his interview, he said a police officer found it first and gave it to him.
And there are other troubling details about what Baker told police and ABC News about the events leading up to that night.
"It's 11 o'clock. She goes, 'Well, go get this movie for me and gas up 'cause we have a busy tomorrow,'" Baker said.
Baker's 45-minute trip was confirmed by surveillance cameras and receipts. When he got home at midnight, he found his wife dead and nude behind a locked bedroom door.
Tom Bevel, a former Oklahoma City homicide detective hired by Kari Baker's family as a crime scene analyst, said paramedics told him that lividity, a reddish rash that normally forms an hour to three hours after death, was just forming on Kari's body when they arrived. He said that indicated that Kari Baker must have died long before Matt Baker left the house for a movie.
Bevel pointed to other red flags, like the locked bedroom door and the typed suicide note, which are rare in suicide cases. He also found it suspicious that the first thing Matt Baker did before calling 911 or attempting CPR was to try and put Kari Baker's clothes back on.
"I knew my wife well enough, that would've been embarrassing for her," Baker said. "I did not want the EMTs to come in and see her naked."
The prosecution's theory is that Matt Baker drugged Kari Baker with sleeping pills and then suffocated her with a pillow.
In an autopsy performed months after Kari Baker's death, there was no sign of sleeping pills in her stomach. There was, however, evidence of sleeping pills found in her tissues, though that does not determine how many sleeping pills she actually took.
The autopsy also failed to reveal any evidence of suffocation or choking.
"I think it is something that, in our society, we hang that hat with the jury and let them look at all of the physical evidence that is there, those issues that you're bringing up, and it is up to them to make that decision," said Bevel.
When asked last year, Baker repeatedly denied killing his wife.
"I loved her. She's the mother of my children," he said. "We struggled after the death of our child and like every marriage, you have your ups and your downs, you have your good days and your bad days. But I loved her and I miss her and I did not hurt my wife."