I'm going to assume that we're talking about text messages (SMS) here. And yes, I do see an app that apparently lets you edit SMS messages called
SMS editor. I haven't tried it so I can't say for sure if it leaves an identifying trail. That would be determined by the app itself and how it modifies the message database. before we can answer that, we'd need to know the app that was used.
Let's talk for a minute about how SMS works with Android. SMS messages are plain text messages sent using a special protocol over the mobile carrier telephone network. When a text message is sent or received it is stored in a protected system database which includes the message, the sender and the date/time. When a message is deleted it is gone from the phone. There are no default backups for messages so if there wasn't a 3rd party backup in place there won't be a record of it.
The carrier, however, does keep a record of messages sent for billing purposes and while the account owner can usually see this on the bill or through online account info, you only see the sending and receiving numbers, not the actual content of the message. The carrier may have the content, too, but I believe that they won't turn that over without a court order.
Let's do a hypothetical here. Person #1 sends a text message to person #2. Person #2 receives the message and then edits it. Person #1 deletes the message from the sending phone. At this point it appears that the altered message on person #2's phone came from person#1. Person #1's phone has no record of the sent message because it was deleted. However, the carrier will show that on a certain date and time a message from person #1's phone was sent to person#2. What it won't tell you is what was contained in that message.
Consider this. It is also possible to spoof a phone number where it appears that a text message was sent from person#1 but they never actually sent it. In that case the carrier may be able to trace it back to the origin, or at least verify that it wasn't sent by the authorized number. You'd have to talk to them about that.
I'd like to ask that others not suggest any legal, moral or ethical opinions and stick only the technical question about editing SMS messages.