(CNN) On the day he was last seen, Jeffrey Navin sent a chilling text message to his son: "Did you hurt mom?"

Two minutes later, another message from father to son was even more ominous: "I go home and get framed for murder."

Jeffrey and his wife, Jeanette Navin of Easton, Connecticut, were last seen on Friday, August 4. Their blue pickup was found four days later by police in a commuter parking lot off an exit on Merritt Parkway, according to Easton Police Chief Tim Shaw.

On Tuesday, their son, Kyle Navin, 27, was arrested and charged with "possession of a firearm by an individual who is an unlawful user of or addicted to any controlled substance," according to federal court records. Kyle has not been charged with any crime related to the disappearance of his parents.

But the court affidavit on the weapons charge sheds some light on the couple's activity on the day they were last seen -- and their interaction with the person who saw them last, Kyle.

Navin's lawyer, Eugene Riccio, did not immediately return calls seeking comment.

Jeffrey and Jeanette Navin were last seen at the trash removal and recycling company that they own, according to Shaw.

The couple went missing just days after losing their latest appeal in a multimillion-dollar foreclosure case, court documents show. He had stopped paying the mortgage in 2007 on a $1.3 million second home in Connecticut, with the debt growing to more than $2 million by the end of 2014, records show.

Family members have said the couple's disappearance is unrelated to their financial woes.

William Navin, Jeffrey's brother and co-owner of the refuse company, told Easton Police that Jeffrey had not shown up to work, which was highly unusual, the affidavit said. He also said that Kyle was the last to see them.

William Navin also told police that family members and friends had been trying to call the couple, but their phones appeared to have been turned off.

Law enforcement officers later obtained cell data for the couple, according to the affidavit. Both phones pinged the same cell tower in Bridgeport, Connecticut -- "in the vicinity of [Kyle] Navin's residence," the affidavit said.

The same day the Navins were reported missing, law enforcement officers spoke to Kyle, according to the affidavit.

Kyle Navin confirmed to police that he saw his parents the morning of August 4 and that they invited him to dinner that evening, but he declined because he was in pain from a back injury, the affidavit said.

Authorities interviewed Kyle Navin three more times during a 10-day period. He gave police inconsistent accounts of the interactions he had with his parents the last time that they were seen, the affidavit said.

Kyle Navin said he picked up his mother at a parking lot off the Merritt Parkway in his garbage truck, and the two went to collect refuse along his usual route, according to the affidavit. Around 9 a.m. that morning, Kyle's back began to bother him and the two eventually met up with his father so his son could go home.

Authorities determined that his varying accounts did not accord with cell phone data, which shows a different travel route for Kyle Navin, according to the affidavit.

Kyle Navin also told authorities he continued to contact his father via telephone that afternoon solely about work and his back injury.

But cell phone records reviewed by law enforcement officers show otherwise:

"I'm not going home till I know mom is okay... did you hurt mom?" said a text message Jeffrey Navin sent to his son, according to the affidavit.

"No Absolutely not. Why would you think," Kyle replied.

"I go home and get framed for murder... I'm going to the police first," the father responded.

Just a half hour before Jeffrey Navin's phone is last registered as being used -- at 12:57p.m. -- there was another text message to his son: "U R setting me up."

Two hours later, a security camera video also captured Jeffrey Navin's garbage truck being driven toward the couple's home late that afternoon with the car of Kyle's girlfriend following behind, the affidavit said.

Nearly 30 minutes later, the girlfriend's car is spotted going in the opposite direction. Kyle Navin's girlfriend later told authorities that Kyle drove his father's truck to their home, she followed him and then drove him back to their residence and "could offer no reason as to why or how Jeffrey's truck came to be in Bridgeport or why Navin needed to drive the truck back to Easton."

Kyle Navin was arrested this week on the gun charge. A detention hearing scheduled for Friday has been postponed with no new date scheduled.

During a search of at Kyle Navin's residence, officers seized two firearms and numerous rounds of ammunition, as well as hypodermic needles, glassine bags with "what appeared to be heroin residue," empty prescription bottle for Oxycodone and several prescription bottles containing various controlled substances such as Xanax, the affidavit said.

Also recovered from the home was a receipt from Home Depot issued on August 5 showing Kyle Navin purchased "germicidal bleach, hair/grease drain opener, 'Goo Gone' stain remover and contractor cleanup bags," the affidavit said.

Law enforcement officers also interviewed a person who had previously purchased prescription drugs from Navin, the affidavit said.

The unidentified person individual contacted Kyle Navin on August 5, to purchase Oxycodone, according to the affidavit.

The person told law enforcement that Kyle Navin said he was "dealing with a lot of family issues and that it looked like his parents were missing."

Navin previously told authorities that he learned about the "mystery" regarding his parents' whereabouts when his uncle called him on August 6, 2015, according to the affidavit.