The idea of the First Officer being the one who spoke in the final received message wasn't 'confirmed' today, as some news sites are saying. In the press conference it was stated that it appears that way. That's not confirmation. Appearances have not proven to be too helpful so far so it is certainly not confirmed.
Also stated in that news conference was that it was not known for sure if the ACARS was switched off before the last vocal message received from the cockpit. It was specified that at 01:07 the last ACARS message was received and at 01:19 the last voice contact was made. Then, there were no more ACARS messages. The official specifically stressed that this is not confirmation that the ACARS was turned off prior to the last voice message...only that is was after the last ACARS message that was received and then the one that should have been received 30 minutes later never arrived.
I'm unaware of any official update to this, which was what happened during the press conference this morning UK time (17th March), so please update me if needed.
I'm finding it irritating that the media is using the word 'confirmed' in their headlines and then using 'suggested' in the meat of the article.