The court heard the 16-year-old victim and two 15-year-old female associates were at the Dunedin Public Library on July 26 last year and met a 16-year-old male associate.
Witchall was a friend of the male and had told him he was 17.
The male introduced Witchall to the females and Witchall was told their ages.
In the library, the group used public access computers to check social media sites.
Witchall became a Facebook friend of the victim and started to engage her in conversation, telling her she was attractive.
When the group went outside and Witchall tried to hug the victim, she resisted.
He became angry and she became scared.
Witchall coerced her into going with him to the library's basement car park, saying he wanted to show her something.
As they walked down the stairs, he grabbed her wrist, led her into a corner and positioned himself preventing her from leaving.
She asked to leave and tried to push past but was unable to get free.
Witchall said he would not let her leave until they had had sex.
He then raped her.
Afterwards, he spent several hours with the victim and her associates and told them he had had sex with her.
Three of the sexual grooming victims were aged 14, the other 15.
The 15-year-old victim was one of the girls Witchall met in the library on July 26.
He obtained her cellphone number and became a Facebook friend, and after texting her about sexual activity, he persuaded her to meet him in the evening.
On August 4, he met her at the library and indecently assaulted her in an aisle. He tried to get her to go to the toilets for sexual intercourse but she was able to distract him and seek refuge.
After obtaining the cellphone numbers of the three 14-year-old victims, and aware of how old they were, Witchall texted them telling them he loved them, trying to persuade each to meet him at parks or school grounds.
He became involved in a relationship with the first victim and continued to text her, continually asking to meet for sex.
They met at a school ground, about 9.45pm on May 24, and he indecently assaulted her.
He began texting the second victim on June 22 and persuaded her to meet him at another school ground.
She arrived with a friend and he tried to kiss her and put his hands around her waist and pull her towards him.
He persuaded her to go out of sight of her friend. She told him she did not want sex with him and left with her friend.
After texts to the third 14-year-old victim, Witchall went to her school on July 29.
At his request, she became truant and spent several hours with him at a park.
He attempted to get physically close to her and embrace her.
When she learned he was 25 and ended the relationship, he denied his age.
Rung by the victim's caregiver and told to leave the girl alone, Witchall abused the caregiver.
Crown counsel Craig Power said the Dunedin offending began just 10 days after Witchall was released from prison.
The pre-sentence report described him as emotionally detached from his offending.
Assessment of him being at high risk of re-offending was ''realistic''.
Public defender Campbell Savage said Witchall knew he was going to have to take a serious look at himself and have rehabilitation treatment through the penal system.
Witchall was also being dealt with on convictions for three other admitted offences - assaulting a fellow prisoner at Christchurch Men's Prison with intent to injure him on April 23; breaching a prison release condition in failing to report to probation on September 11; and failing to attend court at Christchurch on August 18.
His prison term is made up of concurrent sentences as follows: sexual violation, nine years and two months; sexual grooming, two years; indecent assault and doing an indecent act, one year and eight months; assault with intent to injure, one year and two months; breaching a prison release condition, three months; and failing to attend court, one month.
