Uffz. Karl Knichel, 8. JG 53 and 3. Jagdgruppe Süd, US attack at TOULON 29.04.1944

Gentlemen.
my name is Jörg Frank Knichel and I am the grand-nephew of Uffz. Karl Knichel.
This weekend I received a copy of a letter that was sent to my great-grandfather Franz Knichel from Bottrop to inform him about the death of his son Uffz. Karl Knichel, born 29.10.1919.

In one of the threads by Dr. Prien I learned about a huge attack against Toulon (near Marseille in France) by US-bombers on the 29. 04.1944 at noon.
In the letter ist written, that Karl was shot down by US-Fighters that attacked him from the upper rear while he was attacking a 4mot bomber. He went down about 20km south of Port de Bouc at 12.20 hours.

Has anyone information about the attacking bombers or fighters or at least who shot him down?
Pictures and further information are attached to Karls profile.

Regards,

Jörg