[Juha]

Hello Mike
Yes, Trontti was downed on 26.6.44 and Serov got Taran from that. Now Trontti wasn't allowed any credit from Serov's death by the FAF, so FAF probably allocated Serov to Katajainen but Soviet view seemed to be different.

And then corrections. Trontti had 7 kills, but he was a pilot in LeLv/HLeLv 26, so he was Fiat G.50 pilot not Hawk 75 pilot. Got 6 of his kills with G.50 and one with Brewster 239 on 17.6.44 and he was posted to HLeLv 34 on 25.6.44, so he indeed was in all probability on his first Bf 109 sortie when he was downed.
After the war he was a white collar worker in one office and died in 1966! at age of 45. So my memory made a trick once more.

Juha

Ps I checked the Katajainen's combat report on 26.6. He told that he "open fire on a La-5 while turning and then climbed because there were 2 a/c behind me. Lt Saarinen saw that the La-5 I have fired on crashed into Lake Lyykylä..." and as the witness Lt Saarinen wrote "Immediately after we met La-5 Schwarm I saw one plane falling into the Lake Lyykylä"

LATER ADDITION:

according to the info I have Serov crashed at/near village Vammelsuu(nowadays Serovo?) and the Lake Lyykylä is rather far away from that. It is near Tali. I don't have time of Serov's crash but the location (if correct) is IMHO too far away from the place of the victory allocated to Katajainen. Trontti went missing during air combat over Karelia Isthmus (rather vague info) time, probably take-off time, given 11.00. So if Serov was connected with Trontti's disappearance and times are correct then IMHO it is impossible that Katajainen's victim was Serov. I don't know who is connected the Katajainen's claim to Serov's demise. Most if not all Finnish claims on 26.6. seemed to concentrate Viipuri (Vyborg) - Tali area. Lt. Suhonen from HLe.Lv. 24 claimed a La-5 over Tammisuo (between Viipuri and Tali) during his 10.55 - 12.20 sortie and Ylik. Vahvelainen a Mustang (read Yak-9) over Tali on same mission.

It would be interesting research Trontti's downing more thorougly, but I ran out of time.
Juha