In Vanessa's past life, Erin was involved in several illegal businesses. He used his fashion company to cover up where his real money came from.
One of his latest ventures was investing in a new casino business. Casino houses were banned in Graceland, and anyone caught could face jail time unless they were rich enough to avoid it.
Back when Vanessa was still married to Rowen, Erin convinced her to get a large sum of money from Rowen to fund the casino.
He didn't have enough money himself, and the risk was high. If the casino got exposed, he wouldn't just be arrested he'd lose everything he'd ever built.
So he used Rowen as a scapegoat. He got Vanessa to transfer the money through Rowen's account, leaving a clear trail for the police to follow. It made it look like Rowen was the one funding the illegal venture.
