Barty, given the statistical probabilities, it's understandable to focus on the elder scion, but has there been any thought to an investigation into his brother's past? After all, there are eleven years unaccounted. His most recent ... relationship ... excepted, it's not outside the realm of possibility.

Perhaps Mafalda might consider sending someone to ... wherever he crawled off to for all those years. Wasn't it Belfast? (Dear me. Enforced exile to Ireland would be one thing, but self-imposed? I still don't fathom the business. But then, he always did have a tendency toward melodrama.)

At any rate, I cannot imagine he would have been as indiscriminate as his brother, so if you do decide to rule it out, it ought not to occupy your team nearly as long as tracking down all the possible leads the other has left behind.