TAMPA (KNBC/WFLA) — A Tampa doctor who died after contracting COVID-19 left his family one of the most valuable sports card memorabilia collections on Earth.

Dr. Thomas Newman died in January at the age of 73. He spend the last 40 years of his life collecting sports memorabilia.

The family is putting it all up for auction, including the jewel of the collection, a 1933 Babe Ruth card that auctioneers believe could break the $5.2 million world record for a single sports card.

Courtesy Memory Lane Inc.

The collection of sports cards could be worth $20 million, according to Reuters.

Newman’s son says it’s not about the money.

“There was a lot of opportunity for him to get probably the level of notoriety for the kind of collection that he put together over 40 years that he never had when he was alive because he was kind of quiet about exactly the extent of it though. I’m excited. It’s a good thing for his legacy and it will be a fun process to go through,” said his son Stewart Newman.

Stewart said in the 1980s he traveled each summer across the country with his dad to attend the annual National Sports Collectors Convention.

A California auction house Memory Lane Inc. will host the auction which begins on June 21.

“It thrills me to know that collectors that are as serious about it as Tom are going to be able to find things that will give them so much joy.  The kind of joy it gave Tom,” Tom’s wife Nancy Newman said.

A Memory Lane representative said that in addition to Babe Ruth items dating back to his 1916 Sporting News rookie card, other highlights of Dr. Newman’s collection include a near-perfect 1952 Mickey Mantle rookie card (Topps PSA 8) that is expected to sell for more than $1 million. He purchased it in 1986 after it was discovered that year in an original case of 1952 Topps baseball cards in Massachusetts.

He also had baseball cards from Ty Cobb, Lou Gehrig, Honus Wagner, Ted Williams and Cy Young.

Some of the collection was stored at his Tampa medical offices where one room was filled with boxes of still-unopened cards from the 1980s.