Story highlights A man goes missing after he leaves his house on September 2

Nearly seven weeks later, he is found hundreds of miles away

He's found injured and trapped in a ravine; he used the time to write love letters to his family

His death leaves behind many questions

David Welch hopped into his maroon Pontiac Montana van last month and drove for hours. Without saying 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's in the notes is private, authorities say, and they have been handed over to Welch's family.

His family's ordeal started September 2 when he left his home in Manhattan, Kansas.

A day later, relatives contacted the police to report that 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 outdoorsman who loved landscaping, scuba diving and snowskiing, according to his obituary posted on a funeral home's website

Forty-six days after he left home -- on October 18 -- a pedestrian walking along the edge of the desolate road saw an overturned car in a deep ravine.

It was about 850 miles from his home on a deserted section off Interstate 70.

Tire marks led straight off the road down to where his vehicle crashed, authorities said.

It didn't appear that 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, like why was he so far away from home?