NEAR GREENVILLE, Mich. (NEWSCHANNEL 3) - There is an update to an explosion that led to a lock-down at a Montcalm County emergency room.

News reports say deputies identified a person of interest in the case.

Last week someone delivered a package to Derek Lehman's home near Greenville.

A fertilizer bomb inside exploded in his face, burning him.

At this point investigators won't say who they're questioning in the case or what the motive might have been.