Man Pleads Not Guilty to Murdering Mar Vista High School Instructor

Marvin Duncan pleaded not guilty Friday to first degree murder after allegedly confessing to murdering his estranged wife Wednesday, a Mar Vista High School instructor who worked with special needs students.

Updated 4:48 p.m. and 10:31 p.m.

After allegedly stabbing his wife 15 times in the Imperial Beach Sheriff's substation parking lot then confessing the crime as he held his two young children, Melvin Duncan pleaded not guilty to one count of first degree murder Friday at the South Bay Courthouse in Chula Vista.

In a crowd of about a dozen people who came to the arraignment were members of both the victim and suspect's families.

Melvin's wife, Rocio Duncan, was an instructional medical assistant for special education students with the Sweetwater Union High School District since 2008 and worked at Mar Vista High School, according to a district spokesman.

Around 3:30 p.m. Wednesday, the two met in the Imperial Beach substation parking lot to exchange kids when Melvin allegedly stabbed Rocio 15 times in the arms, chest and back of the head, said Deputy District Attorney Ted Minahan.

"The stab wound to the back of the head was done with such force that the knife was lodged three inches into her head," he said.

Melvin and Rocio were married for almost three years and had two young children. The two separated last summer and were meeting to exchange kids Wednesday, Minahan said.

The victim and suspect started divorce proceedings last September, according to court records.

"About a week leading up to the murder the defendant was upset about separation from the victim as well as child custody issues," he said during the arraignment when asking Judge Katherine Bacal set bail at $5 million. "On the morning of the murder he informed an acquaintance he was going to kill the victim and he was going to kill the victim that day."

The arraignment lasted less than five minutes.

It is not known if the Duncan's two children witnessed the murder, said sheriff Homicide Detail Lt. Glenn Giannantonio.

"I know they were present in the area when it occurred but I don't know how much they actually witnessed," he said Friday. "They probably saw some of the contact between the two of them."

There are video cameras outside the substation, but Giannantonio declined to state what cameras caught as they may be used as evidence in Duncan's trial.

Deputies did not hear the altercation between the victim and suspect, Giannantonio said.

"The first they knew of it was when he rang the intercom or pushed the intercom button," he said.

Stephanie Kinnamon worked with Rocio at Mar Vista High School.

"She was sweet and wonderful and loved those students with all her heart," Kinnamon said. "It is sad beyond words."

"The Mar Vista High School staff are in crisis mode because the Moderate to Severe students adored Rocio, and due to their disabilities, they may or may not have any way to comprehend what happened," she said. "They are very fragile."

Principal Wes Braddock said the school's special education students and staff were notified Thursday morning. A school psychologist and other members of school and district staff were there for support.

"They were all there right when school started to inform the kids, and the kids at various levels are able to understand it," he said. About 30 students, two teachers and 10 memebers of support staff are part of the special education class at Mar Vista High School.

Braddock described the special education community as a community within the high school that was shaken by the news.

"She was just a great person, a happy person, the kids all loved her and we're all really sad," Braddock said.

Counselors have been made available to special education students, but Mar Vista High School teachers were urged to send "kids exhibiting signs of angst to the counseling office. That's goes for you too, adults," he said.

A fund in Rocio's honor may be established in the future so donations can go directly to her two children, Braddock said.

"Everybody's really worrying about her kids," he said.

Melvin Duncan, 59, is being held on $5 million bail. He will appear in court on Feb. 21 for a readiness conference and on Feb. 25 for a preliminary hearing. He faces 26 years to life in prison if convicted of killing his 36-year-old wife.

Melvin Duncan allegedly killing his wife is the most recent case of a break up that led to violence.

Last October Vegas Bray pleaded not guilty to a first degree murder charge after her ex-boyfriend Victor Saucedo was shot nine times in the Mariner's Point apartment complex in the 300 block of Caspian Way.

Mike G February 09, 2013 at 04:51 PM
"On the morning of the murder he informed an acquaintance he was going to kill the victim and he was going to kill the victim that day." If the "acquaintance" did nothing to warn the victim or alert the authorities then he or she has blood on their hands too.
LemonGroove February 09, 2013 at 09:15 PM
Our deputies are so encased in their buildings and cars that they have no idea what is really going on around them. How sad.
IBRalph February 10, 2013 at 06:21 AM
In a criminal trial, "not guilty" does not mean "I did not commit that crime". It is a legal word of art to exercise one's constitutional right of a presumption of innocence and have the "people of the state of California" prove that the defendant committed the crime. If the "people's" prosecutor does not offer proof as to each and every element of a charged offense, the defendant's attorney will move to dismiss charges. The defendant's attorney has a duty to provide a vigorous defense even if they feel the defendant is guilty, just as the prosecutor has a duty to provide vigorous prosecution on behalf of the people. The judge will decide issues of law. The jury decides issues of fact, albeit based on the judge's instructions of what evidence is allowed to be admitted before the jury. Sometimes there is no direct evidence, only circumstancial evidence. Each attorney has to make a best guess as to which way the chips will likely fall, so to speak. That's where plea bargaining is most useful. Unfortunately, my opinion is that plea bargaining also has a lot to do with the caseload, and is a way to dispose of cases so that more time is available to try the most serious cases. But if you were charged with committing a crime, wouldn't you want a lawyer who would provide a vigorous defense for you? If we accept less, pretty soon we fall into vigilantism. That is not what this country's laws are based on.
Ibchr February 10, 2013 at 10:11 PM
The acquaintence was his older son. The son did call CVPD and they "apparently" notified the appropriate jurisdiction. How about notifying the intended victim? It would have been easy to find out where she worked. It angers me that this didn't have to happen because people didn't do their job.
LAllo February 12, 2013 at 05:56 AM
lbchr where did you see that?? Have you the link of this information??? Please give it to me. I really need to read it!!


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