BELLEFONTE - An anonymous email. Personal photographs. Flight manifests.

That's how investigators built their case and tracked down the men who say they were abused by former Penn State defensive coordinator Jerry Sandusky, the lead investigator testified Thursday.

Agent Anthony Sassano, of the state attorney general's office, detailed the painstaking steps he and his colleagues took to detect Sandusky's alleged pattern of sexual abuse after a Clinton County high school freshman reported him to the law enforcement in November 2008.

"It was a daunting task to get other victims to come forward," Sassano told jurors on the fourth day of Sandusky's trial. "Everyone here saw these young men testify - to get them to admit to have been sexually abused by a man and to be forced to perform sex acts on that man was tough."

Prosecutors rested their case Thursday, with Sassano and the last three of eight accusers taking the stand. The trial has moved more rapidly than anticipated and could be over by the end of next week.

Senior Judge John M. Cleland, acknowledging the trial's swift pace, said he would give jurors Friday off. Sandusky's attorneys plan to open their case Monday and expect three days of testimony from witnesses including Sandusky and his wife, Dottie.

Cleland, after a lunch delay, told jurors he would give them a transcript of Sandusky's interview last November with Bob Costas of NBC because a portion of audio played in court Wednesday had been repeated.

Sandusky could only laugh after court adjourned Thursday when asked for his reaction to the testimony this week.

"I'm sorry, I can't talk," he said, throwing his arms open. "I can't. The judge has told me not to say anything."

The attorney general's office took over the Sandusky investigation in spring 2009 after the Centre County District Attorney at the time, Michael Madeira, said he had a conflict of interest - his wife's brother was Sandusky's adopted son.

Sassano said investigators searched for potential victims by looking through photographs published in Sandusky's autobiography, "Touched: The Jerry Sandusky Story," and images they recovered through search warrants on Sandusky's State College-area home and a storage room at Penn State that contained the contents of his campus office.

Some of the early accusers provided their own photographs and helped identify others who participated in programs through Sandusky's Second Mile charity and who may have been subject to his abuse, Sassano said.

Investigators seized at least eight photographs of the Clinton County boy, identified by prosecutors as Victim 1, from Sandusky's home in June 2001. Some showed the boy competing in wrestling and track and field events. Others showed him with Sandusky and Sandusky's dog. They found at least six photos of Victim 4, posing in football gear in the Penn State locker room, among the remains from his campus office.

They also seized copies of rosters from the Second Mile summer camps held on the Penn State campus. Some of the names on the list had double asterisks or stars next to them, including those of at least six accusers.

Some of the documents contained handwritten notations of the names of the accusers' mothers and their phone numbers. Another sheet had a handwritten list of the youths' names and shoe sizes.

One juror gasped and put her hand over her mouth as prosecutors projected the list onto a large screen across from the jury box. Investigators went to the campus police department and obtained a copy of a report on a 1998 shower incident that, while investigated briefly, never led to charges, Sassano said. An anonymous email sent to the Centre County District Attorney's office told investigators they "needed to speak with Mike McQueary. He had some information."

McQueary reported that he witnessed what appeared to be Sandusky raping a preteen boy in a shower at the Penn State football facility, on a Friday night in either in February or March 2001 or 2002. McQueary said he had been watching the movie "Rudy," about a former Notre Dame football player, on cable television before going to the football facility. The movie, he said, inspired him.

It also helped investigators narrow down the date of the alleged incident. Sassano said he bought and read through 20 back issues of TV Guide before determining "Rudy" only aired on a Friday night on cable on Feb. 9, 2001.

Then, he said, investigators "sat down and brainstormed" about who else on campus might have seen something during off-hours in the football building.

"Who would be around typically? The janitors," they thought, according to Sassano. The investigators' thinking, and a statement from one of the janitors, led them to an allegation that Sandusky raped a boy in a shower in November 2000.

The investigators subpoenaed a list of janitors from Penn State, Sassano said, but the university "was not very quick in getting us our information."

A television news clip following Sandusky's arrest last November led to more evidence.

While home from work one day, Sassano said, he saw video of Sandusky at the Alamo Bowl in December 1999 with a young man - Victim 4 - standing behind him on the sidelines.

It was Sandusky's last game.

Investigators, he said, obtained copies of Penn State emails related to the trip to the bowl in San Antonio, Texas, including a bus and flight manifest. They also obtained the same documents for the Outback Bowl in Tampa, Fla., the previous January.

The lists showed Victim 4's name just below those of Sue Paterno, the wife of former Penn State head coach Joe Paterno, and Sandusky's wife, Dottie.

Nine years after the Alamo Bowl, someone finally reported Sandusky to the authorities.

"The investigation showed this was going on for a long period of time," Sassano said. "It was kept very secretive and people wanted to keep that secret, I believe."