OAKLAND — Four more people have been charged in connection to a federal visa fraud investigation of the now-closed Tri-Valley University.

On Tuesday, Vishal Dasa, Anji Reddy Dirisinala, Ramakrishna Reddy Karra and Tushar Tambe pleaded not guilty in federal court on charges of conspiracy to commit visa fraud.

The president and founder of the Pleasanton-based school, Susan Su, was indicted by a federal grand jury in April on 33 counts, including conspiracy to commit visa fraud, wire fraud, money laundering, alien harboring and making false statements. She has pleaded not guilty.

According to court documents, the four were charged with crimes related to the school, which federal investigators say was a scam to help foreign students achieve legal immigrant status in the United States by paying “tuition and fees.”

The foreign students lived all over the country and were found to not be physically attending class — a requirement of having a student visa.

According to federal court documents unsealed Tuesday, an undercover Immigration Customs Enforcement agent posing as a prospective foreign student met with Dasa, 25, at the school on Boulder Court in Pleasanton in September 2010.

According to court records, the agent told Dasa he was “completely out of status” in regards to his student visa because he never went to school and feared he was going to be deported.

“So you need some documents, I will prepare some documents for you,” Dasa said.

As they spoke, Dasa prepared the necessary immigration forms, admitted him at TVU and arranged for work authorization.

The charge for this was $2,800 for tuition and fees, of which $1,000 was due immediately.

The agent told Dasa he lived in New York, would not be able to attend class at TVU and he did not have Internet access in New York.

“I will take care of that … There won’t be any problem” Dasa said in response.

A record for that agent was created in ICE’s foreign student database. It showed he was pursuing an MBA and lived in Sunnyvale. The database reflected that the agent maintained an active student status despite never attending a single class.