48 Hours: When a case is a 'slam dunk' -- and when it's not

In our business, reporters often hear police officers and prosecutors refer to cases as "slam dunks." They mean that they believe their evidence is so overwhelming that any jury will give them a conviction.

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It's a tricky view to take, as shown in a complex alleged homicide in the San Gabriel Valley suburbs of Los Angeles.

It was the case of Brian Randone, a charismatic salesman and sometime evangelist, accused of murder and torture in the death of his live-in girlfriend, model and sometime adult film actress Felica Tang. She was 31.

Tang was discovered dead in Randone's apartment on September 30, 2009. Detectives say her body appeared to have more that 300 wounds and scratches. According to Detective Richard Doney, "someone had beat this girl badly."

On examination of the crime scene photographs, one almost recoils at the apparent severity of Tang's wounds--particularly around her face.

In addition, the bedroom of the apartment was a wreck. Police said it appeared a fight had taken place. There was a smashed closet door, blood smears on the wall inside the closet and on the bed. And, according to detectives, there were also a number of signs that someone had tried to clean up the mess.

According to a detective on the scene, Randone said that Tang had taken a drug called GHB, a sexual stimulant and party drug. He also told police she had become upset and uncontrollable, and then died.

Within hours, police arrested Brian Randone (who had "lawyered up"). He was eventually charged with Miss Tang's murder, and more unusually, her torture.

What happened next is a case study how an apparent "slam dunk" case can fall apart.

The prosecution went to court with their case, and then watched it all fall apart. In Randone's defense, his attorneys, led by the well- known L.A. lawyer Mark Overland, argued strongly that there had been no murder at all.

First, the defense attempted to demonstrate that the huge number of injuries on the victim's body were self inflicted. They enlisted a witness, Trinka Porrata, a recognized - though non-medical - expert on the drug GHB. She showed jurors a series of home videos which she said illustrated the extreme loss of control a GHB user might exhibit.

She also said that Tang's injuries were consistent with the kinds of self-inflicted wounds she had seen. She was followed by a medical doctor who supported her views on the dangers of GHB.

The final key witness was a former medical examiner, Dr. Harry Bonnell, who testified that a certain electrical heart signal, called pulseless electrical activity (PEA) was present in Felicia's heart when paramedics examined her after her death. Bonnell pronounced, that given the circumstances of Tang's death, the only possible cause of this PEA was a drug overdose.

In this case, three strong defense expert witnesses shattered what prosecutors had believed to be an unshakeable case.

Greg Fisher is a "48 Hours" producer who investigated Tang's case for the broadcast. Watch the episode online.