DELPHI, Ind. (WLS) – The fourth day of testimony in the Delphi double murder trial is scheduled to continue Tuesday.

Richard Allen is accused of killing teenagers Abby Williams and Libby German near a hiking trail in 2017.

On Monday, the juror had to deal with horrific images from the crime scene.

“One was naked, the other clothed. Both had large cuts on their throats. They both had a significant amount of blood on their bodies and underneath,” said Carroll County Deputy Darren Giancola.

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After the defense heard from two witnesses called by the prosecution, it was time to question them.

Defense attorney Brad Rozzi began a tense cross-examination with Indiana State Police crime scene investigator Jason Page.

Page works for the Indiana State Police in the crime scene investigation division. He was responsible for photographing the crime scene and the girls' bodies.

Rozzi pressed Page about the unspent bullet found near the bodies of Libby German and Abby Williams. This is one of the main pieces of evidence that investigators believe links Allen to the crime.

The defense asked Page why the bullet had not been photographed on the ground more often and why there were a lack of photos of the bullet being removed.

“Wouldn't it be helpful to know that the same cartridge that was pulled out of the ground was going to be used in this courtroom?” Rozzi said.

Page replied, “Yes.” He then continued: “How that affects this case is not my interest. Anything we see that could be evidence, we take a photo of it on the spot.”

Page testified that his primary job was to photograph the crime scene, not to move bodies or decide which DNA to test.

There were also questions about limbs found on and around the girls. Rozzi asked Page if the sticks could have been placed there by someone.

The investigator said: “It was reasonable to assume that it was placed there by some human act.”

The third witness called to the stand Monday was former ISP crime scene technician Duane Datzman.

He arrived at the scene at 1:11 p.m. on February 14, 2017 and took photos from a helicopter.

Prosecutor Jim Luttrell showed photos Datzman had taken.

The photos included aerial shots of the victims in the woods, the girls' bodies, a close-up of Abby's neck injury, and blood on the ground under Libby's foot and leg.

“I kept seeing glitter in the leaves. Underneath the leaves we found a .40 caliber cartridge,” Datzman said.

Abby's mother looked away during the testimony and Libby's mother kept her head down and cried.

Datzman said the three investigators at the crime scene discussed the sticks found between and near the girls' bodies and said they never got any DNA from the sticks because they concluded there was none would have probative value.

On February 15, 2017, he returned to pick up the sticks and took them to the Lafayette Post Office. They also deployed metal detectors over a larger area to see if they could find more evidence.

By this time, the girls' bodies had already been removed.

When the defense team asked Datzman why the girls' temperatures were not taken at the crime scene, he advised against inserting a thermometer into the bodies of girls who may have been sexually abused.

The final witness to testify was Brian Olehy, who was a crime scene investigator for the Indiana State Police.

Olehy described the heavily wooded area where the girls were found as “typical Indiana forest and riverfront” and “prime wildlife area.” However, no trail cameras were found.

The jury had to listen to another witness describe the bloody crime scene. Olehy said he saw some of the girls' clothes turned inside out in the creek and “pools of blood.”

Sticks were placed over some of the girls' bodies, including a larger branch on Libby's arm.

He then told jurors that he and another deputy picked up Libby's body from the ground and placed it in a body bag. He said when she was lifted, leaves and dirt stuck to her back and a large pool of blood formed between the bodies.

Olehy confirmed again that both girls' necks had been cut and that Libby's wound was a result of the “vicious cut.”

Libby's phone was also found underneath Abby in a Harry Potter-themed phone case.

The defense team will cross-examine Olehy when hearings resume Tuesday morning.

The defense also filed a motion regarding the “Down the Hill” video.

“The last thing the girls saw was Richard Allen's face,” Carroll County Prosecutor Nicholas McLeland said on the first day of the trial.

And they heard his “terrifying words: 'Girls, down the hill,'” McLeland said. “The girls obeyed out of fear.”

The defense said the prosecution plans to introduce video and audio enhancements to the original video.

They want to ban testimony about the improved audio. They say allowing a witness to speculate about the words and sounds in the videos would be confusing and misleading to the jury.

The motion also states that the videos were not used to identify Allen as a suspect, so they are irrelevant. The judge will decide on the request later.

ABC News contributed to this report.