The evidence against Wilson was building. Police found a second life insurance on his son. And a second baby from his past who had died mysteriously.
"He had a love for money," says Montgomery County Homicide Detective Meredith Dominick. "He liked to show it, he liked to flash it, he liked to spend it. There was a passion about it."
She says he was willing to commit murder to get it. But what investigators uncovered by 1997 convinced them that Wilson had murdered his own baby boy for insurance money.
Wilson himself gave police a critical piece of evidence when he revealed that he had taken out a second life insurance policy, worth $100,000, on Garrett Michael.
"This was a homicide case," says Dominick. "Missy didn't know about that second policy."
Anastasi claims she knew of only one policy, for $50,000, which Wilson had gotten just weeks after their baby's birth.
But after his son died, Wilson collected on both policies, a total of $150,000. The prosecutor, Doug Gansler, says Wilson spent the money in three months, buying cars, furniture, and paying off debts.
"Missy didn't know, or said she didn't even know, that he had that much insurance on the baby, which always puzzled me," says Adrian Havill, the author of "While Innocents Slept," a detailed look at the case.
Anastasi says Wilson told her that the money came from large commissions he received at work.
During the investigation, police were shocked when they discovered that Wilson had fathered another baby, who had died mysteriously years before he met Anatasi.
"He didn't just do this once, he did this twice," says Dominick. "Not one baby died, but two babies died. There were a lot of dots to connect. We were able to connect them. And it painted a horrible picture."
In 1981, Wilson was 24 and married to a woman named Debbie Oliver. The couple had a baby girl together, named Brandi Jean.
When she was 2 months old, Brandi Jean died of what officials ruled as Sudden Infant Death Syndrome.
"Both cases were so similar. There was this common thread, and that thread was Garrett Wilson," says Dominick.
Wilson had also taken out two life insurance policies on Brandi Jean. He purchased a $30,000 policy from an agent named George Smith.
At the time, Smith had no idea that Wilson had also gotten a $10,000 policy from another agent. "When we first wrote this, I don't think Debbie even knew this was being written," he says.
Hours after his daughter was pronounced dead, Wilson called Smith. "Something was wrong," says Smith. "I knew it. This little girl shouldn't have died."
Smith was so suspicious that he saved Brandi Jean's file. It is the only file he has held onto in this way.
In both deaths, SIDS was the official cause of death. And Dominick and Gansler say that this was a major stumbling block for the investigation.
"It's absolutely, categorically a homicide," says Gansler. "This was a child who was just snuffed out."
After four long years of investigation, police finally arrested Wilson and charged him with the murder of his son, Garrett Michael.
However, Gansler says the case was unable to go forward until the chief medical examiner of the state reclassified the case as a homicide.
"It was not a SIDS death," says Gansler. "They were wrong back then."
More than a decade after Garrett Michael died, prosecutors asked medical examiner Charles Kokes to take another look at the case.
After looking at new evidence, Kokes decided that Garrett Michael's death was a homicide.
The key evidence? "This was not the first sudden infant death syndrome in this family, in association with the father, Garrett Wilson," says Dr. Kokes, who believed that the odds of two such deaths happening in the same family are "astonomically high."
"If two or more children die in the same family, reportedly of SIDS, then there's a murderer in the family, and Garrett Wilson was that murderer," says Gansler, who set out to prove it at trial.
In 1999, Wilson was charged with murdering Garrett Michael. His trial began that year.
SIDS expert Dr. Linda Norton, who reviewed the prosecution case, says that the odds are one in four million. She notes that SIDS is not genetic at all. "I think both of these children were smothered to death, and they were smothered, by their father."
Kokes agreed. "I think this would be considered a cruel death, by anyone's definition."
However, not everyone agreed with Norton and Kokes. "In my opinion, it can't be proved as murder," says Dr. Miles Jones, a forensic pathologist from Kansas City, who testified for the defense.
He says that the cause of Garrett Michael's death was undetermined, and that the cause of Brandi Jean's death was SIDS.
But Kokes believes the brain swelling he found in Garrett Michael is evidence of suffocation: "Brain swelling in Sudden Infant Death Syndrome is rare. That's something that wasn't known in 1987."
Gansler says the scientific evidence was critical. "This was our hurdle to be able to convince a jury that somebody would really be able to kill their own children."
The jury took two hours to come back with a verdict of guilty. Wilson was sentenced to life in prison without parole.
But it wasn't the medical testimony that impressed the jury most. The key, jurors said, was Anastasi's testimony. Testifying was a very important moment for her: "I couldn't bring the baby back, but the least I could do was put him where he belonged."
Vicky Wampler, Wilson's fourth wife and the mother of their daughter, Marysa, still believes that Wilson is innocent.
"What Missy took from my daughter - is she took her father," Wampler says. "I told [Marysa] that her daddy was not coming home - that he was never coming home."
But the case against Garrett Wilson is about to go through another startling turn.
For four years, the man a jury was convinced murdered his baby boy has been serving out his life sentence at a Maryland state prison.
But since 48 Hours Mystery brought you this story last summer, author Adrian Havill says there has been a dramatic development.
"In August of 2002, the Maryland Appeals Court overturned his conviction," says Havill.
The Appeals Court ruled that prosecution experts should not have been allowed to testify on the odds of two SIDS deaths occurring in the same family.
"The chance of that would be one in four million," says Dr. Linda Norton, who testified at Wilson's trial. She says those odds were based on the premise that SIDS is not genetic.
"New research shows that indeed SIDS may be genetic," says Havill. "And there's new medical evidence on that which the Maryland Court of Appeals cited. So they overturned the conviction. Garrett Wilson is technically an innocent man, although he's still in a maximum-security prison."
When Havill spoke to Wilson, he said he was elated and believes that it's just a matter of time before he's going to walk out of that prison a free man.
Does Havill believe that there is reasonable doubt as to whether or not Wilson committed these murders?
"That's a tough one," says Havill. "Did he go into that room, that little baby's room with the mobiles hanging above it and smother his only son?"
Another jury will try to answer that question when Garrett Wilson's new trial begins in September.
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