A considerable number of inmates sentenced to death or life in prison could be innocent, the executive editor of the Texas Observer said in a lecture Thursday.

Dave Mann spoke at MonkeyWrench Books about the death penalty in Texas. Mann focused on specific cases in which he thought the evidence was insufficient to sentence a person to death, including that of convicted arsonist Alfredo Guardiola.

Guardiola, a heroin addict, was on the scene of a house fire in Houston that killed four people, Mann said. Houston police brought Guardiola in for questioning as a witness, but he soon became a suspect, he said.

“People often want someone to blame when there is a tragedy,” he said.

Mann asked the audience of 20 people to be the jury in the case. The audience seemed convinced that Guardiola was guilty, agreeing with the jury that sentenced him to 40 years in prison. Mann then revealed that Guardiola gave a written confession after police interrogated him for 13 hours and showed him pictures of the children killed in the fire. A few days later, Guardiola retracted his confession claiming the interrogators coerced him to confess. Guardiola currently has 20 years remaining on his sentence.

Mann said the case is like many others in which either because of police coercion or botched forensic science, innocent people end up in jail or on death row.

Dallas has re-examined approximately 200 cases, and more than 20 convicts have been exonerated, Mann said. Some areas of forensics, such as blood spatter and ballistics, are currently not sound enough to sentence a person to death, Mann said.

“We can’t have the death penalty until we are close to 100-percent sure that [a suspect] is guilty,” he said. “Judges could be much more discerning when interpreting forensic evidence.”

Scott Cobb, president of the anti-death penalty group Texas Moratorium Network, said capital punishment is an inefficient policy.

“We don’t have a need for it in the U.S.,” Cobb said. “The rest of the world has turned their back on it.”

Of the 20 audience members, the majority agreed the death penalty has flaws.

Mann said a moratorium would be a viable solution to the death penalty.

“It’s a mystery why these cases don’t catch on,” said Mann. “We could use more scrutiny from the media.”

Republican Party of Texas spokesman Chris Elam said the party stands by the death penalty as an option available to juries.

“The appropriate legal authorities have declared it as a viable punishment,” Elam said.