The MACC has been reminded that those under investigation have the right to defend themselves publicly.

"All law enforcement agencies must be open to questions and criticisms and they must not abuse their powers to summon and question persons unconnected to the investigations," Lawyers for Liberty (LFL) executive director Eric Paulsen said in a statement today.

The reminder comes after Selangor Menteri Besar Azmin Ali's aide Yin Shao Loong was summoned for questioning in relation to the MACC's investigations into Menteri Besar Incorporated and Universiti Selangor (Unisel).

Yin was purportedly questioned over a statement he made concerning MACC raids on Unisel and four other places, including MBI and Jana Niaga Sdn Bhd.

He had expressed dismay over the MACC raids on Selangor institutions, which he said was aimed at tarnishing the state government's image.

As the communications director for the menteri besar’s office, Paulsen said it was clear that Yin had no specific involvement in the transactions under investigation.

"He was merely performing his duty as the press officer to inform the public on the menteri besar office’s view on the MACC raid."

Paulsen also noted how the nature of the questions directed at Yin was "clearly irrelevant" as he was asked regarding his tweet stating that he was going to the MACC for questioning and whether he had the authority to issue the statement.

"He was also asked why he had issued the statement before the investigation was completed, which was again irrelevant.

"It was evident that these questions were not serious and unrelated to the investigation. This whole exercise was vexatious and intended to intimidate Shao Loong and others from speaking out while MBI and Unisel are under investigations."

Urging the MACC to be "more professional and impartial in their investigations," the commission was also told to "not be unduly sensitive to public criticisms" regardless of whether they are valid or not.

"Let MACC’s performance on the job speak for itself rather than attempting to stifle public criticism and the freedom of speech and expression as guaranteed under Article 10 of the Federal Constitution."

Following the five-hour questioning last week, Yin had recalled what happened to the late Teoh Beng Hock, whom he said was a co-worker.

"When Teoh went to the see the MACC, he didn't come back. So it's good to let people know where you are," he had said.

Teoh had fallen to his death while under MACC custody in 2009.

The MACC raids are believed to have stemmed from reports lodged against Azmin and MBI over a dispute between Unisel and Jana Niaga.

Jana Niaga allegedly received monetary compensation from Unisel, despite failing to fulfil its contract.

MBI has claimed, however, that the payment to Jana Niaga was made following court arbitration, and threatened to sue anyone who accused it of corruption relating to the payment.