The fact that a body washes up in a particular place does not mean it was put in the water there, especially if a lot of time has passed, which seems to be the situation in this case (about which I know very little).
So, his wife went missing at the end of December, and the body washed up in April. A body can travel a long way in the currents in that amount of time.
Not saying anything about his guilt, just that his saying that when she went missing he was at the place where 3 or 4 months later her body washed up does not indicate anything at all.
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So he was fishing, came home and found his pregnant wife was not there, and put his clothes in the washing machine.
Under other circumstances, he would have been praised for being considerate to his wife!
“A body can travel a long way in the currents in that amount of time.”
Not when it is weighed down by concrete anchors.