Years ago, there was a family who lived just miles away from me. The parents came home from work and found a large pinkish-orange stain in the middle of the white carpet in their (split-level) family room. There were three children, IIRC, a 12 or 15 yo boy, a little sister and a little brother. When the parents asked what the stain was, the two kids the oldest son and at least one younger brother said they spilled Koolaid. When it got dark the parents began to worry because a younger son did not come home.
At some point the police were called. They searched the home/yard and neighborhood to no avail. After what was close to a MONTH, IIRC, the middle brother was discovered. He had been buried in the middle of the backyard, in a yellow plastic bag...under a bunch of fallen leaves. Turns out the boys had been either rough housing or fighting and the younger one died. The older brother , possibly with his little brother's knowledge, buried the brother and cleaned up as best they could. This was probably before OJ and DNA and bringing out search and rescue or even cadaver dogs. One thing that did come out is that the parents knew at least for some time before LE found the body. IIRC, the older boy was charged with the homicide and put into juvenile detention. He has probably been out for a long time. I always wondered how the family could know that their son was dead and buried in the back yard and say nothing. Every time I drive passed that house I think of it. It's probably been 30 years or more.