A San Mateo teenager accused of bringing 10 bombs and other weapons onto campus at Hillsdale High School on Aug. 24, 2009 was fairly competent at manufacturing pipe bombs, according to an explosives expert.
Special Agent Brian Hester, of the Bureau of Alcohol, Tobacco, Firearms, and Explosives, testified today for the prosecution in the San Mateo Superior Court trial of Alexander Youshock.
Hester, who has 10 years of experience with the bureau, made his assessment of Youshock's bomb-building capability based on five pages of hand-drawn designs of bomb prototypes and videos of experiments that were
retrieved from the defendant's San Mateo townhome on the afternoon of the bombing.
Hester took part in the search of the residence and assessed the bins of chemicals and pieces of pipe found there and collected for laboratory analysis.
The drawings displayed numerous concepts of bomb function and design, including ingredients that work best for smoke bombs versus pipe bombs, variations of pipe measurements and attachments, different types of
homemade fuses, and combinations of space, hollowness and fuel load for different bomb prototypes, Hester said.
Officers searching the home also seized a tennis ball that had been modified and contained incendiary material so it would function as a hand grenade, a wooden mortar and pestle for refining and combining bomb-making powders, and a digital scale used to precisely mix and measure those powders, Hester said.
Chief Deputy District Attorney Karen Guidotti played a video that Youshock allegedly filmed of himself mixing and measuring specific quantities of chemicals to make black gunpowder, a common filler for pipe bombs.
Hester assessed Youshock's explosive-making ability on a scale of one to 10 — with 10 being the best — and gave him a six, testifying that the defendant, then 17, did a fairly competent job.
The prosecution is scheduled to continue on Monday.
Youshock is charged with two counts of attempted murder, two counts of exploding a destructive device with the intent to commit murder, one count of possession of a destructive device in a public place, one count of use of explosives in an act of terrorism, and two counts of possession of a deadly weapon.
The defense stated earlier today that Youshock suffers from schizophrenia, which prevents him from discerning between reality and paranoid fantasy.
He faces life in prison if convicted.