According to a report by US broadcaster NBC, Thomas Langenbach was allegedly caught by CCTV cameras changing the official price tags for home-made ones – complete with bar codes.
He was charged with stealing seven boxes of Lego worth a total of about $1,000 from toy stores in the wealthy Silicon Valley towns of Mountain View and Cupertino.
When the state prosecutors then searched his car, they found 32 home-made barcode stickers.
But the more startling find was in his multi-million dollar home, where investigators discovered hundreds of Lego boxes, and found that he had sold 2,100 Lego products for a total of $30,000 on Ebay in the past year.
Supervising Deputy District Attorney Cindy Seeley Hendrickson said Langenbach was only being charged for the four thefts for the time being, while police sift through his immense Lego collection to find what may be legitimately his.
Langenbach calls himself the "vice president at Palo Alto's SAP Labs Integration and Certification Center" on his profile on professional social network LinkedIn. SAP (or Systems, Applications and Products in Data Processing) is a German-based software company, which describes itself as a "market leader" in enterprise application software.
Langenbach has been with the company since 1988 and has a degree in computer science and business administration from a vocational college in Mannheim, western Germany.
The exec was apparently particularly keen on Lego's lucrative "Star Wars" range - the 47-year-old is thought to have re-priced a $279 Lego Millenium Falcon at $49, and a $90 Anakin Skywalker set for about $35.
"This probably happens more often than you'd think," said local police spokeswoman Liz Wylie told NBC. "But this is the first time we've ever had a case like this. Lego is very popular and expensive."