Prosecutors on Friday said investigators found explosive materials, including nitroglycerine, in UC Davis chemistry researcher David Snyder's blast-damaged apartment and said he had been warned in the past not to make explosives at his university's labs.
"He already knew it was against the law," said Martha Holzapfel, Yolo County deputy district attorney.
Ultimately, she said, Snyder "did something so dangerous, even he couldn't control it. This is what he likes to do and he's not going to stop just because you told him, 'No.' "
Snyder, 32, pleaded not guilty at his Friday bail hearing in Yolo Superior Court.
He remains held in lieu of $2 million bail at Yolo County jail on 17 explosives and firearms-related charges connected to the early morning blast Jan. 17 at his Russell Park apartment in Davis.
Prosecutors added seven firearms counts in an amended complaint against the chemist, one each for weapons investigators recovered from the apartment, along with what Holzapfel said were "multiple boxes of ammunition."
Yolo Superior Court Judge David Reed denied Snyder defense attorney Linda Parisi's request to lower Snyder's bail to $500,000, saying his alleged actions put friends, neighbors, colleagues and first responders at risk.
Three weeks after the blast, Snyder sat quietly in the jury booth, his damaged left hand in a substantially smaller wrap than at his first court appearance.
Snyder listened as Parisi described him as an inquisitive tinkerer and hard-working chemist involved in an unfortunate accident.
Though Snyder has family in Texas and Colorado and his stint at UC Davis was to end in January, Parisi insisted the Davis man was neither a flight risk nor a threat to the community.
"There's nothing to suggest animosity or ill will" toward the university, Parisi said, calling Snyder a "prolific worker" at laboratories at UC Davis.
Snyder, who earned a bachelor's degree in chemistry from UC Davis in 2004 and completed doctoral studies in 2011, was a junior specialist at UC Davis on a two-month contract, said campus officials.
Yolo prosecutors quickly sketched out their own portrayal of Snyder as a man with a dangerous penchant for making and detonating explosives.
In Snyder's apartment, prosecutors allege he had several common explosives: a vial of triacetone-triperoxide, known by its initials TATP; hexamethylene triperoxide diamine, or HMTD; and RDX.
Also known as cyclonite, the powerful RDX is a primary ingredient in military C-4 explosives and in blasting caps.
Holzapfel said Snyder remains a danger to the community, citing the explosives, his refusal to talk to authorities who responded to the scene and a call prosecutors say a blast-injured Snyder made to a friend allegedly telling him to dispose of the materials in city and campus trash containers.
Authorities later questioned the unidentified friend. Prosecutors say the person is connected to UC Davis but is not a faculty member.
Parisi downplayed prosecutors' explosives claims following the hearing, saying the materials were in "very small amounts" that would require "some force to detonate."
UC Davis officials declined to comment on Friday's hearing, but said campus administrators in 2011 had received a complaint stemming from a 2009 incident in which Snyder and a classmate allegedly made small firecrackers in a chemistry department lab.
The complaint was reviewed and the case closed, university officials said.
Meanwhile, UC Davis police continue to stress that they had "no evidence to suggest Snyder had broader plans."
Snyder is scheduled to return March 14 to Yolo Superior Court for a prehearing conference.