Try searching for Lydia Decker in any newspaper index and almost any one of them will find this story. I was glad to confirm that this wasn't the Lydia Decker I was looking for.
In summary, Mrs. Lydia Decker lived in Elkhart, Indiana, with her sons, Fred, Calvin, Arthur, and Virgil. Virgil befriended a man by the name of LeRoy Lovett, who resembled Virgil in appearance. On March 12, 1921, Lovett's body was found, near dead, on the train tracks 12 miles west of Warsaw, Indiana, and the initial belief was that he had been struck by a passing train. He died soon after and the body was identified by Lydia Decker who claimed it was her son, Virgil Decker. Her other son, Fred, also claimed it was Virgil Decker. Meanwhile, Lovett's parents claimed the body belonged to their son, LeRoy. The Deckers insisted, but eventually admitted their error. Another autopsy was performed and it was discovered that Lovett died from other wounds, not associated with the train. To make a long story short, Virgil Decker later admitted that he killed Lovett, put his own clothes on him, and then placed the body on the train tracks to cover up the evidence. There was $24,000 in life insurance policies taken on Virgil's life, and the plan was to fake his death to allow his family to collect the money. Unfortunately for Lovett, there was nothing fake about his death. His life was rendered worthless by greed and selfishness.
Virgil Decker was sentenced to life in prison. Lydia Decker received the same sentence but was released on her own recognizance and according to The Elkhart Truth, January 20, 1922 edition, the charges agains Lydia and her other son, Calvin Decker, were dismissed.
This clipping is from the Albuquerque Evening Herald, New Mexico, June 1, 1921. LeRoy Lovett and his wife are shown at top above Virgil Decker and his mother, Lydia, at bottom.
