He is also a convicted sex offender, having had two criminal convictions for molesting a child in 1994 and 2012, and he is currently incarcerated, ineligible for parole until he is 93 years old. Prior to the Soul Giants, Estrada fronted a band called Roy Estrada and the Rocketeers. The group released at least one single on the King label, "Jungle Dreams (Participant 1)" backed with "Jungle Dreams (Participant 2)".
In addition to his work with Zappa, Estrada formed Little Feat with Lowell George, Richie Hayward and Bill Payne in 1969, playing bass and singing backing vocals on their first two albums before quitting in 1972 to join Captain Beefheart"s Magic Band.
Beefheart gave him the nickname "Orejón" ("big ears"). He also played bass for Zappa"s transitional 1976 Zoot Allures touring band, and provided vocals and acting for Zappa"s 1979 film Baby Snakes, and vocal work for the 1980s Zappa albums You Are What You Is, Ship Arriving Too Late to Save a Drowning Witch and The Manitoba from Utopia.
Estrada has also done session work by playing bass for a diverse range of artists, including Ry Cooder on his eponymous debut album, Ivan Ulz, Leo Kottke, Van Dyke Parks and Howdy Moon. In 2002, Estrada joined forces with fellow former Mothers Don Preston and Napoleon Murphy Brock, along with guitarist Ken Rosser and drummer/percussionist Christopher Garcia, to form "The ", the only Mothers of Invention/Frank Zappa alumni consistently performing the music of Zappa since 2002, with over 90 performances.
Since then they have performed at numerous concerts and festivals throughout the United States, Canada and Europe, including Austria, Belgium, Croatia, Czechoslovakian Republic, Denmark, England, Germany, the Netherlands, Italy, Norway and Switzerland.
In 2005, guitarist Miroslav Tadić replaced Ken Rosser in the lineup. Robbie "Seahag" Mangano has been the guitarist for all of the European " tours since 2009. In 2003 Estrada was featured on the album Hamburger Midnight (taking its title from a George/Estrada co-composition on the first Little Feat album) on the record label Inkanish Records, on which he collaborated once again with Jimmy Carl Black.
Estrada served six years in prison after he was convicted of committing lewd acts with a child in Orange County, California, in December 1994.
In January 2012, he pleaded guilty to a charge of continuous sexual abuse of a child which happened in March 2008. In the plea bargain agreement, he was sentenced to 25 years in prison and is not eligible for parole.