IONIA COUNTY, MI -- "Underlying domestic issues" and "accusations of infidelity" are deemed to be significant contributing factors in a Jan. 6 murder-suicide shooting on I-96, according to police.

Ionia County Sheriff's deputies said the shooting, which resulted in the deaths of Lisa Somers, 50, and David Somers, 51, was preceded by an argument in which Lisa accused her husband of infidelity in their four-year marriage.

The argument occurred over the phone and in text messages prior to Lisa Somers and her 18-year-old daughter, Amedy Dewey, flying from Florida to Michigan after the two women vacationed in the Bahamas.

Dewey recounted the incident to sheriff's deputies this week during an interview at Spectrum Health Butterworth Hospital.

"Sheriff's detectives left their meeting with Amedy Dewey with a tremendous amount of respect for the courage, tenacity and strength that this young woman has displayed both during and after this ordeal as she continues to recover from his terrible incident," police said in a press release.

David Somers was booked to attend the cruise with his family, but opted not to go the day before they were set to depart, police said. He picked the two women up from the Gerald R. Ford International Airport in Grand Rapids about 20-30 minutes before the shooting.

The family was en route to Midland, where Dewey was staying with a friend, when police said the couple's argument continued.

David Somers grew angry and began to drive erratically on the freeway at excessive speeds for the road conditions. Police said independent witnesses contacted the sheriff's office to report the erratic driving during the days after the incident.

While on I-96, the man became extremely angry and suddenly slowed the vehicle and pulled it off the roadway before exiting the vehicle, police said.

The two women also exited the vehicle. Dewey told police she heard her mother yell, "He's got a gun!" Dewey got back into the car in the back seat and tried to lay across the seat to hide from David Somers.

Dewey reported looking over her shoulder just before she was shot in the face and shoulder by a single, 12-gauge shotgun slug. Afterward, police said David Somers shot Lisa Somers, before turning the gun on himself.

A loaded shotgun was found beneath David Somers' body. Police determined three shots were fired during the incident.

Police said Dewey called 911 with her cell phone. She honked the horn, used the vehicle's lights and attempted to flag down passing motorists. Witnesses who called 911 told dispatchers they saw someone attempting to wave for help.

Deputies are awaiting the result of a toxicology report to determine if David Somers was under the influence of alcohol or narcotics at the time of the shooting.

Police also confirmed through their investigation that David Somers was being treated for a brain mass or tumor, which may have also contributed to the incident. The extent of how much of a factor the brain tumor was will likely never be known, police said.

David Somers was the subject of a Manistee County Sheriff's Office investigation in 2016 regarding allegations that he committed criminal sexual conduct with a 17-year-old female. He was never charged with the felony, but pleaded guilty to providing alcohol to a minor in connection to the same investigation.

Dewey has made "huge strides" in her recovery progress since being shot in the face and shoulder, according to her family. She transitioned out of Spectrum Health Butterworth Hospital's intensive care unit, and has begun to speak and walk around the halls of the hospital.

"The biggest thing is that it seems her vision may be returning to her right eye," her family wrote on a

created to share updates on her condition Monday. "It's early days yet, but we hope and pray for continued improvement for her eye along with everything else."