His attorney, Deputy Public Defender Tracee Clark, asked that Marvin be released without posting bail.
Marvin has no criminal record, no juvenile record and hasn't been charged with so much as a traffic violation, Clark said.
He is employed, married and financially responsible for four children, Clark said. He has also been a little league coach, a football coach at Benicia High School, and currently teaches a Brazilian Jiu-jitsu class.
"I actually trained some of the deputies here," Marvin told the judge.
Clark said the marijuana charges are for nonviolent offenses and police have not alleged that Marvin had a weapon or that he kept the drugs in the home with the children.
She also noted that her office hadn't received a police report on the drug charges and that one of the allegations appears to have taken place in Solano County, which the Contra Costa County Court doesn't have jurisdiction over.
After privately reviewing the sealed affidavit, Judge Joni Hiramoto said she couldn't release Marvin on his own recognizance. She ordered that his bail remain at $300,000.
Hiramoto did, however, say that she saw no reason for the affidavit to remain sealed. A hearing on the matter is scheduled for Friday.
A preliminary hearing for the marijuana charges has been set for Jan. 3.
Walnut Creek police have said Marvin is their main suspect in the murder of Eric James Martin, 30, who was found fatally shot in his car in a Walnut Creek parking lot Dec. 3.
Police have not said why they suspect Marvin, norhave they indicated what the alleged motive could have been. All they have said is that the two had been acquaintances.