The pictures, recovered from Alexander's digital camera, show Arias and Alexander posing alone in a series of pictures that show their genitals and lubricant on the bed.
There are also a series of photos taken of a naked Alexander in the shower, the last photos taken of the 30-year-old when he was alive. The final photos in the series show a body partly covered in blood on the bathroom floor.
Arias, now 32, has admitted to killing Alexander, but has claimed it was self-defense. She is charged with murdering her ex-boyfriend in a "heinous and depraved" way and could face the death penalty if convicted.
Arias looked away from the screen in the courtroom where the sexual photos were shown, as her mother watched from the gallery. Alexander's sisters, also seated in the gallery, looked away from the photos of their brother.
Computer analysts for the city of Mesa, Ariz., where Alexander lived, went over the photos in detail during the sixth day of testimony in the trial. The photos were time stamped June 4, 2008, beginning around 1:45 p.m.
Prosecutors have said that Arias drove from her California home to Alexander's house, arriving early in the morning on June 4. The pair had sex in the afternoon, took photos of one another, and then Arias killed Alexander, age 30, around 5:30 p.m., they said.
The photos on the bed occurred around 1:45 p.m., according to the data on the camera. The shower photos and the pictures of a bloody body part occurred around 5:30 p.m.
Arias is believed to have stabbed Alexander 27 times in the chest, back, and head, slashed his throat from ear to ear, and shot him the head with a .25 caliber handgun.
In earlier testimony today, the jury watched video taped interrogations of Arias as she repeatedly denied to police stealing and using the handgun that killed Alexander.
Arias told police that she had never seen a .25 caliber handgun and had no idea her grandparents owned one until they reported it stolen a week before Alexander's killing, according to the police interrogation tapes played in court today.
Police from Yreka, Calif., where Arias lived with her grandparents, described the scene of the home when Arias's grandparents reported a break-in. The door was pushed in, breaking the door jamb, and many drawers were opened in Arias' bedroom and her grandparents' room.
The only things reported taken were the handgun, a DVD player, and $30, while other valuable items, including a large pile of quarters and three other guns, were left untouched. Arias told police that her laptop computer was not taken because she had hidden it in a laundry basket covered with clothes.
Officer Kevin Friedman of the Yreka police department told the court today that burglary struck him as odd.
"I believed it was unusual that small items worth money or money, for instance, that the change was not taken," said Officer Kevin Friedman, of the Yreka police department, who investigated the alleged robbery. "I also thought it was strange that only one of the firearms was stolen from the cabinet."
In the police videos, Arias is seen calmly denying stealing the gun from her grandparents' home and using it when she killed Alexander in June 2008, a week after the burglary.
The tapes are the first look at the interrogation and Arias appears to be relaxed as she denies knowing anything about the theft or the murder. She slumps forward at one point with her head almost on the table, and does not appear to be upset when the detective reads the Miranda right to her.
"The gun that was stolen, a .25 auto, just happens to be the same caliber used to kill him," Detective Esteban Flores of the Mesa, Ariz., police department said to Arias after she arrested her in July 2008 for the murder of Alexander.
"A .25 was used to kill him?" she asked.
"Jodi, we're just playing games here," Esteban replied.
"I didn't even know there were guns until my grandparents reported them stolen the day their house was broken into," Arias said.
The prosecution has presented witnesses and evidence throughout the five days of testimony showing that Arias lied repeatedly to investigators before her arrest.
"What did you do with the gun?" Esteban asked her in the video taped interviews.
"I don't have a gun," Arias responded. "I don't know what a .25 looks like."
Arias had previously told Esteban in phone calls and interviews that Alexander had inexplicably stopped returning her phone calls, that she had taken a road trip to Utah to visit a man she was interested in dating that Alexander was killed, and that she had never used a gun or been violent.
Arias later admitted driving to Alexander's house in Mesa, Ariz., where she killed him, before continuing onto Utah to meet her new love interest.
Police allege that Arias arrived in Mesa from California, that she and Alexander had sex, took sexually graphic photos of one another, and then Arias brutally attacked Alexander, killing him.
She then drove to Utah to see Ryan Burns, whom she kissed and cuddled with for a day before returning to California.
Alexander's body was found five days later in a pool of blood in his bathroom by his friends.
Arias lied to Burns and to cops about the trip to Mesa in the months leading up to her arrest, before she confessed and said the killing was in self-defense.