One juror suffered a panic attack and a police officer was assaulted during chaotic scenes at Leeds Crown Court after the conviction of Jamie Sharlotte on May 2 this year.
Sharlotte's mother, Angela Midwinter, 53, and sister, Kimberley Sharlotte, 28, ran from the public gallery and swore at the jury.
Kimberley Sharlotte told jurors: "You...lot are dead."
Midwinter also referred to one of her son's victim's as a "druggie" and insinuated to the jury that they had got the verdicts wrong.
The pair appeared in the dock at Leeds Crown Court after pleading guilty to contempt of court.
Lawyers for Midwinter, of Barncroft Grange, Seacroft, and Sharlotte, of Langbar Square, Swarcliffe, said they had behaved out of character and were sorry for their actions.
Both were fined £250 and ordered to pay £300 court costs.
Judge Guy Kearl, QC, said: "It is natural that when a verdict is entered by a jury that there is desperation and distress, particularly for those associated with a convicted defendant."
"What is not acceptable is an outpouring of rage, anger and violence within a court towards the police, jury, barristers and the court in general.
"This was a concerted action.
"You advanced out of the public gallery towards the bar, the bench and the jury. You were shouting and screaming at everyone in court.
"The jury were rooted to the spot. They were shocked and panicked.
"This was a show of force by your family against the court, the police and jury.
"They were left terrified, distressed, upset and worried about how they were going to leave the building in safety.
"All they were trying to do was do their public duty.
The court heard a police officer in the public gallery was attacked during the incident and suffered bruising to his head and face.
A 34-year-old man and a 16-year-old male pleaded guilty to assault and affray at an earlier magistrates court hearing.
The 34-year-old was given a 26-week prison sentence, suspended for two years, ordered to pay do 150 hours of unpaid work and pay £150 costs to the injured officer
The 16-year-old was made the subject of a referral order and told to pay £150 compensation
Jamie Sharlotte, 25, was given an extended prison term totalling 12 years after Sharlotte was found guilty of two attacks on women in Leeds in April and October 2016.
The jury heard he followed a woman into a quiet street after she got off a bus in Cross Gates on the afternoon of April 25, 2016.
He pulled her to the ground, put his hand to her throat and tried to remove her trousers, but fled when she continued to struggle.
Sharlotte struck again in Seacroft during the early hours of October 26 as he walked to work at Leeds Market.
He followed a woman along York Road at 3am, forced her to the ground then carried out the sex assault.