Charges in connection with the death of Penn State freshman Joseph Dado are expected to be filed by the end of the week, though authorities are remaining tight-lipped as to what the now-concluded investigation revealed.

"This has been a complex case that has required a lot of checking and re-checking of facts," Penn State spokeswoman Lisa Powers said.

The State College Police Department and Penn State Police worked together on the case, which included an

investigation into whether any individuals or organizations provided Dado, 18, with alcohol in the hours leading up to his death, Powers said.

Toxicology test results recorded Dado's blood alcohol content (BAC) at .169 percent and found no drugs in his system, Centre County Coroner Scott Sayers said. Pennsylvania's legal driving limit BAC for 21-year-olds is 0.08 percent.

Before maintenance workers found Dado's body at the bottom of an exterior stairwell near the Steidle Building on Sept. 21, the freshman had attended events at two fraternities -- Alpha Tau Omega, 321 E. Fairmount Ave., and Phi Gamma Delta (Fiji), 319 N. Burrowes Road, friends have said.

After leaving Alpha Tau Omega, Dado and a group of friends went to Dado's sister Natalie's apartment, friends said. After that, the group went to Fiji, police said.

The Interfraternity Council (IFC) suspended both fraternities pending the investigation's conclusion.

Dado, of Latrobe, was last seen alive leaving Fiji at about 3 a.m. Sept. 20, police said. Dado was seen leaving the fraternity alone, authorities said.