(CNN) -- David Welch hopped into his maroon Pontiac van last month and drove for hours. Without expressing where he was going, he kept on driving, police say.
Nearly seven weeks later, a hitchhiker found him in a deep, isolated desert patch in Utah, hundreds of miles from his Kansas home.
Injured and trapped in his car, he'd spent his final days penning love letters to his wife of 32 years and four sons.
Authorities say his car plummeted into the ravine in early September after it veered off the road.
Welch, 54, sat in his mangled car for days, maybe weeks, police say. Nights became days, then weeks, then over a month.
And as his family searched for him, he was trapped in his car, scribbling his last words.
What is in the letter is private, authorities say. But the notes have been handed over to Welch's family.
His family's ordeal started on September 2 when he left his home in Manhattan, Kansas.
A day later, relatives contacted the police to report he had not returned home.
"At this time officers confirmed that there was no reason to believe Welch was currently in danger of harm or had known medical issues that may cause him to be in danger," the Riley County Police Department said.
It said it notified law enforcement agencies in areas where Welch may have gone.
Four days after he left home, a missing persons report was filed. Long stretches of time passed with no news of his whereabouts.
The retired Pepsi Co. representative was an avid outdoors man who loved landscaping, scuba diving and snow skiing, according to his obituary posted on a funeral home's website.
Forty-six days after he left home -- on October 18th -- a pedestrian walking along the edge of the desolate road saw a car tucked in a deep ravine.
It was about 850 miles away from his home on a deserted section off of Interstate 70.
Straight tire marks led off the road down to where his vehicle crashed, authorities said.
It didn't appear like he was braking or attempting a turn, just that he went straight off the road, said Cpl. Todd Johnson, a spokesman for the Utah Highway Patrol.
Authorities believe Welch fell asleep while driving, sending the car crossing into the ravine and rolling onto its passenger side, CNN affiliate KSNT reported.
Welch was trapped alive in the ravine for an unknown number of days.
He was found dead. What police don't know is how long he lived.
And with his passing, a lot of questions remain unanswered, like why he left his family to begin with.
CNN's Sonya Hamasaki, Drew Iden and Jennifer Feldman contributed to this report.