On the planet Noveria, head to the hotel bar and look for a Turian named Lorik Quinn. Accept his quest to steal the data from his office. Once you get the data, the receptionist will ask you to get Quinn to testify. Tell her you'll do it, and then go talk to Quinn. From here:

1) Tell Quinn that he should testify (top left option)
2) When he refuses, select the Charm option (top left) for Paragon points or the Intimidate (bottom left) for Renegade points and end the conversation
3) Talk to him again, and ask about the Matriarch
4) When he gets done talking about her, select the "Other questions" option (bottom right)
5) Now, you'll have the option to ask him to testify again (top left). He'll refuse, and you'll be able to use the Charm or Intimidate option again to gain another 24 Paragon or Renegade points

Repeat as many times as you want!