A judge ordered him held without bail on Wednesday afternoon after the Tulare County District Attorney's Office charged the 69-year-old with eight felonies.
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Seven are child molestation charges from 2002 - the alleged victim-a 6-year-old boy.
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"Different crimes have different time for statute of limitations, and in sex crimes, the statute of limitations is significantly longer," said Tulare County Assistant District Attorney David Alavezos.
The family of the alleged victim contacted police after hearing about Sierra's arrest late last month.
Police say he was standing outside his home when he made eye contact with a 10-year-old girl and started to touch himself.
She was in her father's vehicle at the time, waiting for him to finish some work he was doing in the area.
RELATED: Registered sex offender arrested after exposing himself in front of 10-year-old Porterville girl
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Police say Sierra then went inside his house, where he got naked and continued to touch himself while staring at the girl through a window.
For that case, the DA's office has charged Sierra with felony indecent exposure.
Sierra was convicted of indecent exposure another time, back in 1992.
He was also convicted of assaulting a family member with the intent to rape her in 2002.
Sierra will be back in court next week. He faces more than 40 years in prison.