The problem isn't so much about finding them than it is about retaining them. Male teachers tend to leave the profession before the end of their 20
s. Some start in their semi-retirement days, but that's quite rare.
Surprisingly I had 2 science teachers and 1 math teacher that were Engineers in previous careers but decided to move into teaching (far before retirement age).
Maybe with programs like http://www.teachforamerica.org/ we'll start seeing more professionals change careers into teaching.
Anecdote: I had a family friend move into teaching from engineering but he found it hard to find a job not teaching in the ghetto or for schools catering to troubled teens and after a few years moved back into engineering.