The mother of a boy who won a large settlement from Michael Jackson over alleged abuse, said the singer begged her to let her son share his bed.
Mr Jackson denies the allegations against him
At the trial, June Chandler said she initially refused to let teenager Jordy Chandler sleep in Mr Jackson's bed, but relented when the singer got upset.
"He said, 'You don't trust me? We're a family... There's nothing wrong,'" she told the court in California.
Mr Jackson, 46, denies charges of molesting a different 13-year-old boy.
Judge Rodney Melville has allowed past accusations against Mr Jackson to be brought up at the trial, as permitted under Californian law.
Prosecutors are trying to establish a pattern of child sex abuse, alleging that five boys were molested or groomed for abuse by Mr Jackson.
Previous allegations against Mr Jackson have never been proved in court and are denied by some of the alleged victims.
Ms Chandler who was in court on Monday was testifying about alleged abuse against her son, Jordy. The family received a reported $20m (£12.7m) out-of-court settlement from the singer in 1994.
She testified that she and her then 13-year-old son stayed at Mr Jackson's Neverland ranch for the first time in February 1993, but she initially refused to let her son sleep in the singer's bed.
However, she said she relented when during a trip to Las Vegas the following month, the singer tearfully asked her why she would not allow it.
"He was sobbing and crying, shaking and trembling," she said. "He said, 'You don't trust me? We're a family.
"'Why can't he sleep in my bed? There's nothing wrong. There's nothing going on.'"
From then on, she said she always allowed the pair to share a bedroom, including for weeks at a time when Mr Jackson visited her family in southern California.
The woman admitted in court she had not spoken to her son for 11 years. He is not expected to testify in the trial.
Mr Jackson is charged with molesting 13-year-old Gavin Arvizo at his Neverland ranch two years ago, plying the boy with alcohol and conspiring to commit false imprisonment, child abduction and extortion.
He denies a total of 10 charges. If found guilty, he could face up to 20 years in prison.
Several former employees at Mr Jackson's ranch testified last week, saying they had seen him fondling and abusing boys there.
The star's defence has sought to portray them as money-driven and vengeful.