Editor's note: CNN contributor Bob Greene is a best-selling author whose books include "Late Edition: A Love Story" and "Once Upon a Town: The Miracle of the North Platte Canteen."

(CNN) -- It started with a 5-year-old boy who had the decency to do the right thing.

It is about to end with tragedy layered upon endless tragedy.

Eric Morse, who was 5 in 1994, was asked by some older boys in his Chicago neighborhood to steal candy for them.

He said no. He didn't want to steal.

The older boys, who were 10 and 11 at the time, determined that Eric, who was growing up in a home marked by frequent parental absence, must be punished for his honesty. The 10-year-old, according to court documents, had an IQ that was below 60. The 11-year-old had an IQ of 76. They had led wretched lives of neglect and squalor.

On October 13, 1994, the two older boys encountered Eric and Eric's older brother, Derrick Lemon, who was 8. They asked Eric and Derrick if they would like to see a clubhouse.

Eric and Derrick agreed to follow the older boys.

The older boys led them to an abandoned apartment on the 14th floor of the Ida B. Wells housing project, a high-rise building that had the reputation of being a home base for drug dealers.

They led Eric and Derrick into the empty apartment. It is where they would execute Eric.

The older boys lifted Eric up and dangled him from an open window.

His 8-year-old brother would testify later that he was able to grab Eric's arm and pull him back in.

But then, Derrick testified, the two older boys ordered Eric to look out of a second window. If he refused, they said, they would strike him in the head with a brick.

Eric, afraid, complied. The older boys then picked the 5-year-old up and dangled him out the second window.

Again, his 8-year-old brother tried desperately to save him. He grabbed on to one of Eric's arms.

But, Derrick would testify, one of the older boys, seeing that he was trying to rescue his little brother, bit the hand with which he was holding Eric. With the boy's teeth sinking painfully into the flesh of his hand, he had to let go.

Eric's body dropped 14 stories. Derrick would later testify that he ran down all 14 flights of stairs. He believed, he said, that he might be able to get to the bottom in time to catch his brother.

The two older boys were almost immediately arrested by Chicago police. They were found guilty of murdering Eric. A judge sentenced them to be held in a juvenile prison until they turned 21. They were 11 and 12 at the time of the sentencing hearing.

There was much discussion at the time about what would happen to them, and to their communities, once they were released. The fear was that, without extensive psychiatric help, they would emerge from juvenile prison as adults who were a threat to society. And in fact, since their release, both have been in and out of Illinois prisons for various crimes.

Which left the fourth child who was in that 14th-floor apartment that October day in 1994: the 8-year-old brother, Derrick.

He received some counseling, but at a court hearing some years after Eric's murder, the social worker who treated Derrick testified that she had deep concerns about what was happening to him.

He was all but emotionally dead, she testified. He was haunted by the memory of the murder, she said, and about what he perceived as his failure to hang on to his brother and save his life. She said that he was depressed, anxious, and was unable to cope with daily pressures.

In her testimony, she told the court: "He thinks of himself as almost worthless."

No one knew with certainty then what would become of Derrick. And no one knows, even now, the totality of the factors that have formed his life.

But here is what happened last week:

In a Cook County criminal courtroom, prosecutors asked a judge to send Derrick Lemon away for a long prison term.

He is 24 now. He stands guilty of murdering a man named Illya Glover at a family barbecue in 2006. Glover was shot to death when he tried to stop Lemon from attacking a female relative at the gathering.

Lemon will be sentenced next month. He faces a term ranging from 45 years to life in prison.

Seventeen years ago, a 5-year-old boy did the honest thing by saying he would not steal the candy for the older boys. Somewhere, in his dismal and impoverished childhood, he had figured out that there was a difference between right and wrong, and that he should choose right.

Soon after, the older boys whose demand he had defied invited him and his brother to that supposed clubhouse on the 14th floor.

And since that moment, only anguish without end.

The opinions expressed in this commentary are solely those of Bob Greene.