Foul during FT

[Freddy]

Originally Posted by Camron Rust

...wasn't there an NFHS interpretation a couple of years ago that said crossing into the FT semi-circle and fouling the FT shooter should be an intentional foul (if before the FT is dead)?

Search of NFHS Interpretations came up with nothing on that score.
Below is the 2015-16 Interpretation issued before 9-1-3h was included in the book the next year. I recall this being distinctive because it, at that time, seemed to deem mere contact with the free thrower a foul. But I don't recall "Intentional" being any part of it during this clarification process.
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Clarification Preseason Guide Article “Enforce Illegal Contact on Free Thrower and Violations During Free Throw”, page 6, second paragraph: The free thrower must remain within the free throw semi-circle until the ball contacts the basket ring or the shot is made or missed. The same rule applies to all other players who do not occupy free throw lane line marked spaces. Players who occupy free throw lane line marked spaces during free throws may enter the free-throw lane upon the free thrower releasing the ball; however, should a defensive player cross the free-throw line too soon, it is a violation. A delayed violation signal is to be displayed. If the free throw is successful, the violation is ignored. If a defender contacts the free thrower, a personal foul is the correct ruling. If the free throw is unsuccessful, the violation is enforced and a substitute free throw is awarded. If a defender contacts the free thrower, a personal foul is the correct ruling. Whether the free throw is or is not successful, the penalty for the personal foul is awarded. If the free thrower’s team is in a bonus situation, the free thrower would be awarded a one-and-one or two free throws. If the free thrower’s team is not in a bonus situation, his or her team would be awarded a throw-in along the end line.

SITUATION 1: The opponent makes contact with the free-throw shooter before the free throw reaches the basket. The free throw is missed.
RULING: The official should rule a violation on the opponent and a personal foul. (9-1-2g Penalty 2b)

SITUATION 2: After A1 releases the ball on a free throw try, B1 steps into the lane and backs across the free-throw line to box out the free-throw shooter then makes contact with the free-throw shooter. The free throw is missed.
RULING: The official should rule a delayed violation on the opponent. A1 will be awarded a substitute free throw and the contact is ruled a foul. The substitute free throw would be administered with the free-throw lane spaces unoccupied. (9-1-2g Penalty 2b)