[Cry Me A River]

IMHO, a terrible idea.

If she's involved, she's extremely unlikely to admit anything and even if she does, except for his own "piece of mind", what good does it do? It's his word against hers. Why would she believe he'd cover for her after she just tried to rob him?

And right now, she has no idea he suspects her. This completely tips his hand and he looses all advantage. Hell, for all he knows she does have a boyfriend, the boyfriend freaks out at the thought of getting busted and comes for a visit carrying Mr. Louisville Slugger or Mr Smith and Mr Wesson.

Finally, on the remote chance that she's completely innocent, he's essentially accusing her and she's likely to be seriously offended.

If he's really interested in taking her down, he absolutely should only do it with the cops if they're up for a sting.

Otherwise, he should just stay the hell away from her and beef up his home security just in case she/they try to make a run at his house anyway.