The first school to offer Castro was UCLA, who did so last summer when he was wrapping up his sophomore year at Vista Murrieta.
This past weekend, Castro took in one of UCLA's spring practices.
"It was great at UCLA this weekend," said Castro. "I spent time with the D-Line coach (Inoke Breckterfield) and the head coach (Rick) Neuheisel. They took me on a tour and to practice."
Castro got the early UCLA offer, but the Bruins weren't as high on his list early in the process.
That appears to be changing.
"They're definitely still a school I'm considering," said Castro. "I love how they're improving day by day to get better."
Next up will be a trip to Seattle.
"I'm going to Washington on the 28th," said Castro, who will visit the Huskies for the Spring Game with his Vista Murrieta teammate and Washington signee Derrick Brown.
For now, though, Castro said he's got no leader.
"No leader right now, I'm wide open and considering everyone," said Castro.
Last fall, Castro had 118 tackles, 13 sacks, eight for loss, three forced fumbles and two fumble recoveries.