It's been nearly a week since Adam Lanza gunned down 20 children and six women in Newtown, Conn. and we are still no closer to knowing what motivated the, by all accounts, reclusive 20-year-old to kill.

Investigators have revealed Lanza destroyed the hard drive on his computer before shooting his mother Nancy, driving to Sandy Hook Elementary School and using her guns to kill 20 children and five teachers. They believe Lanza spent most of his time in the weeks leading up to Dec. 14 playing video games on his computer in the basement of his home.

Without the computer, it will be difficult to figure out whether Lanza had mentioned his plans to anyone online or whether Lanza left behind some sort of vendetta revealing his motives for the crime. The Hartford Courant spoke with an expert in computer forensics:

Depending how the metallic disk at the center of a computer hard drive is broken or cut into pieces, it can be difficult or even impossible to retrieve information, said Eric Friedberg, New York- based, co-president of Stroz Friedberg, a computer forensics and investigations firm.

"It is hard to put Humpty Dumpty together again," Friedberg said. "I have never actually seen this done – but the physics would say that you could do it. If it is in three or four pieces the physics suggest that it is conceivable."

Investigators are still, however, attempting to get whatever they can off Lanza's computer, as well as his cell phone. They're also continuing to investigate the crime scene at Sandy Hook Elementary, where police are picking up bullets, and going over video surveillance at nearby gun stores, to see if Lanza tried to buy a gun in the days before the shooting. All three guns he brought into the school were legally purchased by his mother, Nancy.

One of the biggest problems with the investigation is that, aside from online, Adam Lanza appeared to have very little interaction with anyone besides his mother, whom he killed.

Lanza had no job, never used social media, seemingly had no friends and rarely if ever had any contact with his brother or father.

A new report from HLN suggests Nancy Lanza had left her son home alone from Tuesday to Thursday of last week, just one day before the shooting. Lanza had just returned home from a two-day trip to Bretton Woods, N.H. when her son shot and killed her Friday morning. The New York Post reports friends of Lanza's say she often took short trips, leaving Adam home alone.

[Hartford Courant // Image via AP]