In those piles, Athay will find statements made to police by Hacking's parents, brothers, co-workers and friends, all of whom have provided information leading to criminal charges.
Athay will also find testimony from Lori Hacking's co-workers, the couple's neighbors and witnesses who believe they saw Lori or Mark, or both, in the hours surrounding her death.
Among those witnesses will be Amy Bagwell of Farmington, who was walking in Memory Grove Park at 6 a.m. the day Mark Hacking reported his wife missing. Bagwell saw a man fitting his description smoking a cigarette in a car that was similar to Lori's.
"It might sound weird, but he gave me a creepy feeling," Bagwell told The Salt Lake Tribune on Tuesday. "He had an angry look on his face and I didn't want to go anywhere near him."
How fast the case moves may depend on the extent of Athay's own investigation, in which he will search for holes in each witness' testimony that might lead jurors to have a reasonable doubt about Mark's culpability.
For instance, while Bagwell's recollection seemingly places Mark in the park where Lori's car was found hours earlier than he supposedly awoke on that morning, Bagwell acknowledges she can't be positive about whom she saw.
It was two days after the search began that Bagwell called police after learning that Lori's car had been located at the park.
David Finlayson, president of the Utah Association of Criminal Defense Lawyers, said the so-called "discovery" stage of the case could take considerable time.
"Gil's going to be gathering information and figuring out what they've got for evidence," Finlayson said. "It'll take months."
Finlayson, who represents accused Elizabeth Smart kidnapper Wanda Eileen Barzee, said the discovery in that case consists of tens of thousands of documents.
Athay also will be talking to prosecutors at the Salt Lake County District Attorney's Office.
"I expect there has already been extensive dialogue on this case," said Salt Lake City defense attorney Mark Moffat. "And while they may or may not be negotiating a resolution, certainly there's been an open channel of communication between Athay and the DA's office."
Moffat believes a plea agreement, if any, would be weeks or months away.
"As a defense lawyer, you want to be in command of the facts, you want to know what all the facts are before you negotiate with the state about a potential resolution," Moffat said. "You want to assess the strength of the prosecution's case and strength of any defenses, to know if an offer is appropriate."
The next major step in a felony case is the preliminary hearing, where the prosecution must present enough evidence to convince a judge there is probable cause to believe a crime was committed and that the defendant committed it. Defense attorneys will want to have thoroughly digested the evidence before proceeding to the preliminary hearing.
"They will also be following up on their own leads and ideas relevant to defenses or holes in the prosecution case," Moffat said. ''Sometime the defense will want to conduct their own investigation of the case. Also, you may hire your own forensic experts. A good defense lawyer never takes the prosecution's experts at face value.''
Meanwhile, Athay may ask for a bail-reduction hearing, where a judge would assess Hacking's risk of flight and danger to the community. He currently is being held in lieu of $1 million cash bail.
"In high-profile cases, a bail reduction is hard to come by. But there's no harm in trying," Moffat noted. "You are better served by having your client out of custody. He's more accessible to you, and it's easier to discuss discovery and strategy.
"But with a very serious crime, you have to look at practical realities. If there is a reduction, it may not be much. It may not be anything your client can afford."
Athay may also ask the court to inquire into Hacking's mental competency - his ability to appreciate the charges against him and assist his attorney in his defense. But Moffat said many defense attorneys first obtain a private competency assessment by hiring their own mental-health expert.
"Your own expert is cloaked in the attorney/client privilege," Moffat said. "If you rush to file [for a competency inquiry], it can lead to disastrous consequences. The client might say things or do things that could hurt your defense.
"You want to have a legitimate belief [he is not competent]. Otherwise you can march him into a process that yields unfavorable results."
According to Moffat, "A good attorney will consider any defense."
In the Hacking case, that could include pushing for quick preliminary hearing and trial settings in an attempt to obtain a verdict before Lori Hacking's body is found.
Because the woman was purportedly five weeks pregnant, discovery of her body could lead to capital murder charges.
But Moffat cautioned that the body is just one item of evidence. "It may not be the determinative item of evidence," he said.
"If the evidence in absence of a body is very weak, a lawyer may consider a quick trial," he said. "But if there is a great deal of circumstantial evidence, it may not serve the client to rush to trial.
"It's completely dependent on the nature of the evidence the prosecution has."
Prosecutors have said that if the body is found and if Lori Hacking was pregnant, they could amend the current murder charge to a capital crime - as long as a trial has not occurred.
The Constitution protects against a defendant being tried twice for the same crime.
Even if a body is found, medical experts said it would be a daunting task to determine whether she was pregnant.
"It would be difficult. Not impossible. But difficult," said Howard Adelman, a retired New York City medical examiner and forensic consultant.
The best way to determine pregnancy, of course, would be an autopsy. But the results would depend on the condition of the body and the degree of decomposition, which may vary widely depending on many circumstances.
Still, with the victim dead for approximately three weeks and the body exposed to the heat of the summer, the uterus would have significantly decomposed, said Kevin Cooper, director of pathology and laboratory medicine at Wadsworth-Rittman Hospital in Wadsworth, Ohio.
Although Cooper does not have forensic training, he said a blood or urine test for pregnancy-indicating hormones would also be out of the question, as those break down within a few days.
Testing the blood found in Lori's car and the couple's apartment probably would not reveal pregnancy evidence because it probably had already dried by the time it was found, rendering it useless for those purposes, Adelman said.
Tribune reporter Ashley Broughton contributed to this story.