Torrez was the investigating officer after Mostrong's van struck a golf cart and two people, including Michelle Marie Grady, 17, of Alpine, who died at the scene. The accident occurred on Wheeler Road in the western Imperial Valley desert.
The prosecution is asking the jury to find Mostrong, 21, of El Centro guilty of vehicular manslaughter, driving under the influence and hit and run.
Espinosa has claimed Michelle and those she was with had been drinking the night she was killed and has argued the golf cart was stopped in the road with its lights off, making it impossible to see.
Under questioning from Robinson, Torrez said based on the investigation he determined the crash occurred at 11:54 p.m. Oct. 7. He arrived at the scene shortly after midnight Oct. 8.
Robinson asked Torrez if he was able to determine the speed of the van when it struck the golf cart, Michelle and her friend, Eric Welter, who survived the accident.
Torrez responded he did, but before he stated the speed Espinosa objected and Contreras sustained that objection, which meant Torrez could not state the estimated speed.
However, Robinson asked Torrez how he goes about determining speed and Torrez responded brake marks in the road are one method.
"How many brake skids did you see from the defendant's vehicle?" Robinson asked.
"None," Torrez said.
Robinson asked Torrez about his interviewing of those in the van with Mostrong at the time of the accident.
Robinson asked about Chris Purdy, who testified he was in the van and after the collision, he took the driver's position from Mostrong and he drove them from the scene until the van suffered a punctured tire in the desert.
"Did Mr. Purdy tell you he had driven away in the van?" Robinson asked.
"No," Torrez responded.
Robinson asked Torrez if Purdy had said during his interview with Torrez that he recalled seeing lights ahead on Wheeler before the crash.
Torrez responded, "Yes."
In his testimony last week, Purdy said he did not recall specifically seeing lights ahead on Wheeler.
Robinson asked Torrez if at any time he badgered the witnesses or put words in their mouths. Torrez said he did not.
Torrez further testified that Mostrong turned himself in to the Highway Patrol at 4 p.m. Oct. 8, about 16 hours after the crash.
He said Mostrong came in the office with an attorney.
Torrez testified Mostrong did not want to submit to a chemical test of this blood. Torrez testified Mostrong had a conversation with his attorney, after which Mostrong said he had marijuana in his system.
Robinson asked Torrez if it looked like Mostrong had been up all night.
Torrez said, "No."
Torrez said it was his opinion that the primary factor contributing to the collision was driving under the influence of alcohol and/or drugs.
Torrez said driving at an unsafe speed for conditions was a factor on the driver's part in the collision. On the victims' part, Torrez said unsafe stopping on a roadway was a contributing factor.
Espinosa asked Torrez if the victims had been "making out." Robinson's objection was sustained and Torrez did not answer the question.
Espinosa asked Torrez if he'd seen the wounds sustained to Welter's testicles. Torrez said he had not.
In a question stricken from the record, Espinosa asked Torrez, "Are you aware those are bite marks?"
Robinson quickly objected.
Much of the remainder of Espinosa's cross-examination Monday focused on whether the golf cart lights were on and how Torrez determined the van's speed at the time of the collision.
Torrez responded he used witness accounts to determine the lights had been on and had taken into account visibility and lack of brake marks to partly determine the van had been traveling at an unsafe speed.
The day's testimony ended as the golf cart's vehicle code violations were brought up.
Staff Writer Darren Simon can be reached at 337-4082. Staff Writer Kelly Grant can be reached at 337-3441.