Hackman and Arakawa, who have been married since 1991, were found dead at their home in February.
Earlier this month, the New Mexico medical investigator's office revealed that Arakawa and Hackman both died of natural causes. Their deaths happened at least a week apart and are attributed to different causes.
FILE - Actor Gene Hackman arrives with his wife, Betsy Arakawa, for the 60th Annual Golden Globe Awards in Beverly Hills, Calif., Sunday, Jan. 19, 2003. (AP Photo/Mark J. Terrill, File)
Betsy Arakawa and Gene Hackman. (AP)
Authorities had previously based Arakawa's likely date of death on what they'd pieced together about her activity, stating that Arakawa's last known communication was on February 11.
She was seen on surveillance video going into stores that day before coming back to the gated community where they lived at around 5.15pm. However, after obtaining cell phone data, investigators have learned Arakawa used her cell phone on February 12.
"We can now confirm that Mrs Hackman's phone was utilised on the morning of February 12 to call a medical centre in Santa Fe, Cloudberry Health. A total of three calls were made that morning, all to the medical centre," the Santa Fe Sherriff's Office said in a statement.
This undated photo provided by Sherry Gaber shows Betsy Arakawa with her dogs Zinna, left, and Bear, in Santa Fe, New Mexico. (Sherry Gaber/AP via CNN)
"One incoming call was made to Mrs Hackman from the same medical centre that afternoon. That appeared as a missed call on Mrs Hackman's cell phone."
Arakawa, 65, died of Hantavirus pulmonary syndrome, a rare disease that can infect humans through contact with infected rodents, according to the New Mexico medical investigator's office. Her body was found on the floor of a bathroom in the couple's home.
Hackman, 95, likely died several days after Arakawa, on February 18, when his pacemaker last recorded his heartbeat, authorities have said. The Oscar-winning actor died of causes related to cardiovascular illness and had advanced Alzheimer's disease, which authorities said was "a significant contributory factor" to his death.
Legendary actor Gene Hackman's life in pictures
The couple had three dogs: Zinna, Nikita and Bear. Zinna, an Australian Kelpie mix, was found deceased in a kennel in the bathroom where Arakawa was found. However, the couple's surviving dogs have been adopted into new homes.
"In response to numerous concerned inquiries about the Hackman's dogs, both Bear and Nikita have been placed in appropriate homes," the personal representative for the estates said. "Both are safe, healthy and adjusting to their new environments."
According to astatement on the Santa Fe County Sheriff's Facebook, the German Shepherd and the Akita-shepherd mix were found roaming the Hackman's property. The home's front and back doors were left ajar, allowing the dogs to wander in and out.
The Santa Fe County Animal Control Division worked with family to make sure the dogs were kept safe.