Surveillance footage captured the unidentified man approaching the gift box of cards and cash as guests waited in line to greet the bride and groom.
In the video, he drapes his coat over the box, appears to glance around and then carries off the box without being noticed.
Maribel and Anthony Nolasco got married in Monrovia, California. After they noticed the gift box missing, they looked at the surveillance tape and saw the guy pacing the area.
"I found out earlier in the reception of what happened and I didn’t tell my wife until the whole reception because I didn’t want to break her heart with any type of bad news," Anthony told Inside Edition.