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. Last Updated: 07/27/2016

DNA Blood Tests Implicate Simpson, Prosecutors Say

LOS ANGELES, California -- In the strongest evidence to date against O.J. Simpson, prosecutors revealed that his blood has the same genetic makeup as blood drops leading from the slashed bodies of his ex-wife and her friend.

But a major battle likely will be waged over the statistical odds that the blood drops at the crime scene came from the former football star.

The prosecution released its findings in court papers Monday, saying it would be useless for the defense to conduct its own sophisticated DNA tests because the results will not clear Simpson.

"The DNA tests conducted so far implicate the defendant," prosecutors wrote.

The DNA evidence is expected to be the crux of the prosecution's case since there are no known witnesses to the June 12 slashing deaths of Nicole Brown Simpson, 35, and Ronald Goldman, 25.

Simpson, 47, is set to go to trial Sept. 19 on murder charges.

Prosecutors have alleged Simpson left blood at the murder scene after cutting his finger during a struggle. Defense attorneys have provided a variety of explanations for the cut.

Peter Arenella, a University of Los Angeles law professor, called the test results "very significant evidence."

But he noted that the prosecution has two major hurdles ahead: persuading Judge Lance Ito to allow the evidence into trial, and convincing a jury there is an extreme likelihood the crime-scene blood is Simpson's and not somebody else's.

The prosecution papers suggested blood matches, but did not include a breakdown of the statistical odds of such matches.

In a 1992 report, a committee of the National Research Council wrote: "To say two patterns match, without providing any scientifically valid estimate (or, at least, an upper bound) of the frequency with which such matches might occur by chance, is meaningless."

Dr. Michael Baird, vice president of laboratory operations for Lifecodes Corp., a forensics lab in Stamford, Connecticut, disagreed.

"These tests are so powerful and so discriminating that even a match without statistics is significant," Baird said.

Simpson's lawyers will likely argue that the population sample used to calculate the frequency of Simpson's blood type could indicate there are other people with the same genetic markers -- perhaps even another killer.

In the court papers, prosecutors contend that two samples from the blood trail leading away from the murder scene showed a match with Simpson's blood.

One of those samples also was subjected to a more sophisticated DNA test, sometimes called DNA fingerprinting, and the results showed the banding pattern of that blood matched Simpson's.

At a preliminary hearing last month, a police criminalist using standard serology blood testing said Simpson's blood type matched blood found at the murder scene and only 0.43 percent of the population could have left the blood.

According to the prosecution's papers, the DNA tests also found that blood in the foyer of Simpson's home the day after the killings had the same genetic makeup as Simpson's blood.