A fallen billionaire's bulletproof Mercedes sold at bankruptcy auction for $63,000. Here's how it went down.

Joe Buglewicz for BI

• Business Insider took a deep-dive look at the bankruptcy auction of an armor-plated Mercedes.
• The auction was entirely online, and people placed 115 bids without kicking the tires in person.
• Here's what happened in real life — a four-year process ending when the "gavel" fell on Thursday.

How do you auction off a former billionaire's armor-plated Mercedes?

As with virtually every bankruptcy auction these days, there's a one-word answer to that question — online.