BOISE, Idaho (ABC4) — On the 19th day of Lori Vallow Daybell’s murder trial, it was revealed that her brother’s phone data put him at the scene of the crime for both JJ and Tylee’s murders.

Rexburg Police said that according to their investigation, Tylee was murdered sometime between Sept. 8 and 9, and JJ was murdered in the early morning of Sept. 23. Both of their remains were eventually found buried on Chad Daybell’s property.

The last time Tylee was reported seen was Sept. 8 at Yellowstone National Park. It was reported that Tylee was at the park with Lori, Lori’s brother Alex Cox, and JJ. The last known image of Tylee was at Old Faithful in the park.

According to Rick Wright, a contract special investigator for the FBI, it is likely Tylee returned to the apartment after Yellowstone, as phone data for Cox on that day did not show any unusual stopping or deviations.

However, on the morning of Sept. 9, Cox’s phone data puts him at Lori’s apartment from 2:42 a.m. until 8:49 a.m. According to Wright, this was unusual behavior for Cox. During the entire month of September, Wright said Cox’s phone data showed that Cox would always return to his own apartment around midnight. Wright said this was the first time he observed Cox at Lori’s apartment between the hours of midnight and 6 a.m.

Then at 9 a.m. on Sept. 9, the data on Cox’s phone showed him traveling to Chad Daybell’s house, where he remained until approximately 11:45 a.m. At 11:53 a.m., Chad texted Tammy and told her he shot a raccoon and buried it in their pet cemetery. He said he found the raccoon when he was burning the “limb debris” by the fire pit. Tylee’s remains were found at the pet cemetery near the firepit.

The last time JJ was reportedly seen was Sept. 22, and according to RPD, he was killed the morning of Sept. 23. Wright said on Sept. 22, “There was some traffic with the device.” Between 4:29 p.m. and 12:11 a.m., Cox went back and forth between his and Lori’s apartment. There were also other visitors at Lori’s apartment that night.

Cox’s phone stayed at his apartment between 12:11 a.m. and 9:41 a.m. on Sept. 23. However, at 9:41 a.m., Wright said Cox’s phone data showed him traveling to Chad Daybell’s home, where he arrived at 9:55 a.m. Cox stayed at Chad’s property until 10:12 a.m. According to Wright, the data showed him near the pond. This is the same area where JJ’s remains were found.

Wright said that based on his training, experience, and knowledge working with the FBI, 17 minutes was not enough time to dig a hole, dig a grave, place stones, etc. He said it is possible that more than one person was involved in burying JJ.

Phone data also showed Cox at a church about two miles from Chad Daybell’s property on Oct. 19, the day Tammy Daybell died. Police could not identify anyone else Cox knew living in the area other than Chad. From 10:45 p.m. to 11:53 p.m., no location data was recorded on the phone. The next location was at 11:53 p.m. near a US Highway.

According to Rexburg Police, Tammy Daybell died of asphyxiation at the hands of another, between the hours of 12:30 a.m. and 2 a.m. Detectives and coroners testified in court concerning Tammy’s death on Friday.

To read more about the trial, visit ABC4’s Lori Vallow Daybell Murder Trial.