BOSTON -- The Boston Strangler's brother is scheduled to make a very public challenge to prosecutors Thursday when he gives a blood sample in hopes of proving Albert DeSalvo's innocence.

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NewsCenter 5's Gail Huff said that Richard DeSalvo is going to have his blood drawn in front of television cameras. He said that he wants the public to know exactly where the blood came from.

Albert DeSalvo claimed to be the Boston Strangler. The last of his alleged victims was Mary Sullivan. She was murdered 37 years ago.

Albert DeSalvo's family believes that he did not kill Sullivan. They had Sullivan's body exhumed earlier this year in search of new DNA evidence.

In hopes of proving his brother's innocence, Richard DeSalvo agreed to give blood during a news conference Thursday so that investigators can look for DNA comparisons.

Prosecutors have been asking for a blood and saliva sample since the case was reopened.

"Frankly it's put up or shut up. We want the sample from them," one prosecutor said. "If we get it, it is the only course of action we can take now to try to obtain some type of result that may result in a viable prosecution or any inclusions or exclusions that relate to Albert DeSalvo."

Richard DeSalvo said that in exchange for offering his blood sample, he wants evidence that was collected at Sullivan's murder scene.

Prosecutors said that they have not reached a deal with Richard DeSalvo.