He is accused of raping his young cellmate in Upper Hutt's Rimutaka Prison on multiple occasions, as well as forcing him to perform oral sex every night from mid October 2017 to early January 2018.
He is also alleged to have threatened to kill the complainant if he reported the alleged offending or tried to move to a different cell, at one point pulling a shank on the man.
The complainant gave evidence in court yesterday, saying if he refused to engage in the sexual acts Goundar would slap and punch him repeatedly until he complied.
The alleged abuse ended when an anonymous tip-off was made, and Goundar was moved out of the unit. The complainant gave a statement to police later in the year.
All the accusations are denied, with defence lawyer Karun Lakshman saying the complainant was "making it all up".
Today, a fellow inmate who lived in the neighbouring cell told the court how the complainant seemed "scared" of Goundar.
The inmate moved into the unit some time after Goundar and the complainant began sharing a cell. He said he worked in the gardens with the complainant, but did not get along with Goundar.
"[The complainant] was very scared of Ben, I know that," he said.
He described him as a "very shy and withdrawn boy" and he saw the complainant regularly obeying orders from Goundar, such as orders to collect his lunch for him, go take a shower, and fetch water and brooms to clean the cell.
He said Goundar's tone was "very abrupt" and "standover-ish" (sic).
The inmate said he also heard Goundar refer to the complainant as his "bitch" quite a few times. He also claimed to have heard banging, groaning and moaning sounds coming from the cell at times.
The day Goundar was taken out of the unit, the complainant "started to come out of his shell again" and seemed "very excited and happy", he said.
Lakshman accused the witness of making his evidence up.
"These complaints or allegations you've just made ... these are not true, are they? You're saying all these things because you have a bone to pick with Mr Goundar, don't you?"
The inmate agreed he did not like Goundar, but denied making the allegations up.
Referring to the inmate's evidence of the complainant seeming happier when Goundar was removed, Lakshman pointed out that the complainant's friend had then moved into the cell with him, and this could be something that would make him happy and excited.
The inmate agreed that would be a situation that would make someone happy.
The trial will continue through the week.
Where to get help:
• If it's an emergency and you feel that you or someone else is at risk, call 111.
• If you've ever experienced sexual assault or abuse and need to talk to someone call the confidential crisis helpline Safe to Talk on: 0800 044 334 or text 4334. (available 24/7)
• Male Survivors Aotearoa offers a range of confidential support at centres across New Zealand - find your closest one here.
• Mosaic - Tiaki Tangata: 0800 94 22 94 (available 11am - 8pm)
• If you have been abused, remember it's not your fault.
• Wellington HELP has a 24/7 helpline for people who need to speak to someone immediately. You can call 04 801 6655 and push 0 at the menu.