Program Note: For more details on the killing of Annie Le, a Yale medical student, watch AC360° tonight at 10 p.m. ET.

Le, 24, a Yale graduate student was found the day she was scheduled to marry her college sweetheart.

Randi Kaye| BIO
AC360° Correspondent

I covered the brutal murder of Yale medical student Annie Le in September.

She’s the 24-year-old lab student whose body was found stuffed inside the wall at one of Yale’s labs on campus.

They arrested and charged an animal research technician, Raymond Clark III, who is still locked up.

At the time, we all wondered, what the heck happened? Well, today, we know a lot more.

I just got my hands on the arrest warrant affidavit which has some fascinating new details about what led police to arrest Ray Clark and charge him with strangling Le to death.

The affidavit appears to show that Clark was trying to cover his alleged tracks right in front of the officers investigating the murder.

Authorities say they found Le's body in the basement wall of a Yale medical research building.

Police say Clark raised eyebrows immediately when he allegedly tried to move a box of wipes that were splattered with blood out of the direct line of vision of a police officer. The wipes were on a cart in the lab and according to the affidavit the officer says she watched Clark turn the box around in attempt to hide the blood.

Also, while officers were casing the lab for clues, they say Clark began scrubbing the floor grate and drain with SOS pads and cleaning solution. That surprised them since they said it did not appear to need cleaning. And officers say Clark even changed his clothes at least once while the FBI was processing the scene. What’s up with that?

Another disturbing find: a pair of men’s work boots with blood-like stains labeled “Ray C” written on the back of the boot. The shoelaces were missing. As if that isn’t enough, the affidavit says a sock found at the scene had both Clark’s DNA on it, as well as DNA belonging to Annie Le.

The most damaging piece of evidence may have been found inside the wall cavity where Le’s body was hidden. There with it, a green ink pen. Why is that significant? Because Clark’s lab workers told police at the time of the murder that he would always sign in to the lab with a green ink pen to separate himself from everyone else. The day of the murder, police say Clark used a green pen to sign in to the building. Authorities say the pen was found under Le’s body and that it had her DNA on it as well as his. His DNA was found on the pen’s cap.

Before they were finished, investigators say they also found a lab coat with blood stains on it that’s a size XL. Clark is seen on video taped footage from inside the lab wearing a lab coat on the day of the murder. Investigators say they also noticed Clark had a scratch on his left arm and one on his face, but that Clark told police his cat had scratched him at home. Also, Clark’s movements inside the lab building made police suspicious. They tracked his key card which is necessary for access and, according to the affidavit, Clark used his key card to gain entry into the room where Le worked and another room 55 times from 10:40 a.m. to 3:45 p.m. the day Le disappeared.

According to the affidavit, Clark told police he knew the victim, Annie Le, for about four months but that she left the building about fifteen minutes before him the day of the murder. Clark has not yet entered a plea and is due back in court later this year. Do you think police have a solid case?

Find the full affidavit here.