Policarpio Espinoza Perez and Adan Canela have been mentioned in the same breath since they were charged nine years ago in Baltimore with slashing the throats of three young relatives, ages 8, 9 and 10. They have sat side-by-side at two trials, but as prosecutors this week make a third try at convicting them, each man will get a chance to tell his own story.

The change could allow the defendants to challenge the prosecution's theory that they were both involved in the Northwest Baltimore murders — another hurdle for a prosecution already without key pieces of evidence from the last trial seven years ago.

E. Wesley Adams III, a former Baltimore homicide prosecutor who was not involved in the case, said it is generally more difficult to convict defendants separately. "It's like watching a TV show with only one character."

Perez, 31, an uncle of two of the victims, will begin his trial Monday. Canela, 26, a cousin of theirs, is scheduled to face a jury later this spring.

The illegal immigrants from Mexico are accused of brutally murdering Lucero Espinoza, 8, her brother Ricardo Espinoza, 9, and their cousin Alexis Espejo Quezada, 10, at their apartment in the 7000 block of Park Heights Ave. in 2004.

The bizarre case captured the region's attention and focused on a complex family tree with roots in a small Mexican town. Defendants, witnesses and victims share common relatives — some here and some abroad — making it harder for investigators to untangle what happened on the day the children died.

The men's lawyers say the separate trials will allow them to shed new light on parts of a story that has eluded explanation for years.

"For the first time everyone's going to hear exactly what my client said," said Nicholas Panteleakis, Perez's attorney, referring to a police interview in which his client claims never to have entered the apartment where the children were nearly beheaded.

Police arriving on the scene later described it as one of the most gruesome they had ever encountered.

Officers soon found a 10-inch knife they believed was used in the crime, and a neighbor picked out Canela and Perez at the scene, saying she'd seen them acting suspiciously near the apartment a few days before. Subsequent searches turned up what police said was bloodied clothing.

But confusion about the evidence left jurors unable to agree on a verdict the first time the case came to trial in 2005. The Baltimore State's Attorney's Office tried again the following year, securing convictions that were overturned because of judicial errors.

Canela's lawyer, Brian J. Murphy, said he thinks the evidence has always been weaker against his client and that the juries will now have a chance to weigh the case of each man more carefully.

"Even though the jury's supposed to consider each one separately it's hard to do," he said. "You're sitting in the same boat."

The state's attorney's office declined to comment on the case, following its usual policy.

But Tony Garcia, a former prosecutor who handled the first two trials, said securing a conviction has become "harder, but it's not impossible."

Lawyers for Perez and Canela won a number of pretrial rulings to have prosecution evidence — including much of the DNA used last time — barred. Guadalupe Juarez Hernandez, a key witnesses, is now in prison in Mexico, convicted of arranging the murder of her husband Victor Espinoza Perez, and it is unclear whether she will be available at trial.

Garcia said prosecutors will have to be creative in constructing a narrative around the killings without Hernandez. He relied heavily on her testimony during the last trial.

"She is extremely important to the case," he added. "She is the center of the wheel, everything else is a spoke from her."

On top of that, prosecutors will have to deal with the added workload of trying the case twice, back-to-back.

Perez and Canela have been linked since the neighbor identified both of them, and Garcia said the evidence suggested that both men were present during the killings. But prosecutors have never been able to conclusively establish a motive for the attacks.