Prosecutors in a Sumter County double murder trial may have had their biggest day yet.

The defendant, Bill Marquardt, claimed he wasn't in Florida during the 2000 Tarrytown murders. He was removed from a mental health facility in order to stand trial for the murders.

However, DNA evidence proves he was at the scene, prosecutors said.

Prosecutors said inside a house 11 years ago, Marquardt left his DNA behind when he murdered two women. Marquardt, however, insisted that he has never been to the Sumter County cottage where Margarita Ruiz and her daughter Esperanza Wells were brutally murdered 11 years ago.

Prosecutors said they can prove he was there through DNA tests that were conducted on blood that was splattered around the house. 

Florida Department of Law Enforcement analyst Darren Esposito said one such sample included a mixture of DNA belonging to Ruiz, Wells and at least one other person.

"And when I compared the profile from Mr. Marquardt, he is included as a possible contributor to that mixture," said Esposito.

Detectives also said Marquardt's pistol that was found under the refrigerator in his Wisconsin cabin a couple of weeks after the killings was the murder weapon. They said that's because the bullets found in the victims and casings found around their house match the gun.

"I was able to positively identify the three bullets in front of me as having been fired from the Stoeger Arms pistol," said FDLE crime lab analyst John Romeo.

Detectives said in March of 2000, Marquardt murdered his mother in Wisconsin, drove to Florida and killed again.  Marquardt said he was framed for the Tarrytown murders by fellow drug dealers. 

Showing his lack of legal experience on Wednesday, Marquardt, who is representing himself in court, slipped up when asking crime lab analysts about his gun marked exhibit number 55.

"And did exhibit number 55 turn out to be the murder weapon? Or, or, strike that," Marquardt said in court.

Prosecutors will wrap up their case on Thursday, and police from Wisconsin are expected to testify.

Marquardt will begin calling his witnesses on Friday.