Events occurring at Assassination Time

[AussieMick]

From what I see, the Whig Press printed editions on the Wednesday of each week. I guess its possible that a special edition for Friday 14th could have been printed.

I see (according to Newspaperarchive) only 5 newspapers (such as Indianapolis Daily Journal) printed some details of the assassination on the 15th April ... but it is possible those newspapers may have had the habit of printing an edition with "yesterday's " date so it appeared as if they were first with the news. (Like some glossy magazines now have their February 2019 issue in the shops)
Or they had a 'late' edition.
The other thing is that it is conceivable that a newspaper (maybe not the Whig Press) got lucky. There have been instances where the death of the Pope or Queen Elizabeth have appeared in a newspaper by mistake. Every newspaper has these type of stories stored away for when the time comes ... maybe the newspaper in 1865 on April 14th printed an error which came to be true.
Coincidences do happen ... But, no, .... I think we'd all know about it if it happened.