Three days after I left my house, Detective Hernandez called me into her office.

I sat down across from her, and I could tell from her face that she had it, whatever it was, the thing that turns a feeling into a fact.

“We had a problem,” she said, “and then we had a solution.

The problem with identical twins is that on a standard DNA test, the kind most people imagine would settle a question like this instantly, their profiles come back so nearly identical as to be useless for telling one from the other.

If we had only had DNA, we might never have been able to prove which brother was which.