Carlo, not Carlos. It could be the cops still have not established a motive, IMO. Mercado probably just got stopped randomly at the San Onofre checkpoint because he looked Hispanic. His guns/silencer were confiscated and he was allowed to drive away. This is a border patrol checkpoint. They handed the gun charges off to the state authorities (the DA). Under that scenario, investigators would not normally perform ballistics on the weapons. They would just inspect them to see if they were illegal, inspect the magazines to see if they were illegal, and obviously the silencer was illegal in California. To run a ballistics test -- which required firing the guns into objects -- does not make sense at that point.
However, according to the prosecutor, his DNA was taken at the time of his arrest on April 29. (He bailed out and was charged with felonies May 5). The prosecutor said his DNA was not in the CODIS system until his arrest in April. Bingo, when they run his DNA they get a match, assuming they had already found suspect DNA at the San Diego crime scene and/or perhaps on the steering wheel of Gianni's vehicle in Riverside. If they obtained fingerprints or partial fingerprints, they would also get a match at the time of Mercado's arrest in April. Then and only then do they start doing ballistics on the weapons. And maybe it takes a month to do those tests. Bingo again, they get a ballistics match. Under this scenario, they have their man via DNA or fingerprints or ballistics but they may not have a motive. Still, they have a solid case WITHOUT a motive so they arrest him. Only after his arrest in Mira Mesa do they serve a search warrant and seize his computer. That may help them BEGIN to establish a motive. Listen to that extended Q and A with the prosecutor above, he is specifically asked IF they have a motive. He dodges the question. He also says any motive is still possible.
Keep in mind Mercado has ABSOLUTELY NO CRIMINAL HISTORY until after the murders when he gets caught with the weapons. IMO, that tells me he is not a druggie. The fact that he worked at Target for the past EIGHT YEARS as a stock boy indicates he is not a professional hit man. Of course, somebody could have hired him knowing he liked guns and had a clean record. The cops/prosecutor give no indication that they believe there is an accomplice running around free.
Love or infatuation could still be the motive. But somehow, Mercado had access to know Ilona's pickup routine at the mall. He could have taken out Gianni first and was then waiting for Ilona and did not expect Sal to show up. There are also reports that Mercado rode a motorcycle. Maybe he drove Gianni's vehicle up to Riverside? Who knows. I think the cops are still trying to figure all this out. Certainly, they will be able to track Mercado's cell phone pings that night.
