On New Year’s eve of 1965, Katherine Radican’s family received terrible news. Her brother-in-law had died in a plane crash. For almost five decades, Katherine’s husband searched the 18-square-mile long Folsom Lake of Sacramento only to find one sign of the long-lost shell of the plane that took his brother away, a mystery that might have been unfolded way before, during the drought in California with the help of modern technology, ABC reported.

“My husband made a vow to her dying mother that he would keep searching for his brother’s remains and perhaps finally give him a proper burial,” said Katherine.

Katherine’s husband, Frank Wilcox, died three years ago without fulfilling his promise and the chapter was ended once and for all.

But recently, some researchers made a startling discovery while testing a sonar device at the Folsom Lake. They found what appeared to be the debris of a small plane that might have been crashed around the 1960s.

“We were testing our sonar technology and I saw something that was not normal,” researcher Tyler Atkinson told ABC.

Tyler said that the new sonar device detected something underwater, that seemed artificial. It was in the deepest part of the lake and the water was too murky to tell what it was.

“We decided, okay, there’s definitely something down there, and maybe it’s the plane,” said John Tamplin, president of the research company.

Then last week, Riley and Atkinson came back to the spot with a small underwater vessel and sent it down in the waters to look for the findings but the attempt failed. 

Riley and Atkinson went back for the third time, but this time they attached a sonar device with the vessel to get some underwater images. This time, the vessel came back with the astonishing images of a fully intact Piper Comanche 250 plane covered in silt, said an ABC report.

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The drought in California, Folsom Lake, helped in the discovery of the 56-year-old plane. The lake, which has the capacity to hold 975,000 acre-feet of water, went down to about 361,000 acre-feet of water due to the drought, said California Department of Water Resources data released in May.

Radican, with a sigh of relief, told ABC News that the plane was found at the bottom of what used to be a section of the American River before Folsom Dam was built in 1955.

She also told that her late husband had searched the area during a drought in 2014 with the help of a different sonar company but came up empty-handed.

According to the Roseville Press Tribune, the aircraft carrying Wilcox’s brother on his first flight collided in midair with a small Beechcraft Debonair sightseeing plane at an altitude of about 2,500 feet.