UNDATED (KTHV) – One of Jerry Garcia's famous guitars, ‘Wolf’ is going back on the auction block at the end of the month.

The Grateful Dead legend's instrument previously sold for about $1 million in 2002 at Studio 54, becoming the most expensive guitar ever sold. The buyer wants to support the Southern Poverty Law Center in its fight against hate groups and racism, which is why the guitar will go back on sale.

Jerry Garcia, Larry Hulst/Michael Ochs Archives/Getty Images

The auction will take place May 31, only days after the Martin Scorsese-produced documentary about Jerry Garcia and the Grateful Dead comes out.

Fans interested in bidding should visit Guernsey’s website or contact the auction house. To read more, click here.