PHILADELPHIA — An aide to state Sen. Vincent Fumo admitted Monday that he conspired with the longtime power broker to destroy e-mails and other evidence during an FBI extortion probe that eventually led to the lawmaker's indictment.

Computer technician Leonard Luchko's guilty plea comes a month before Fumo's scheduled federal trial in what proved to be a far-reaching corruption case. The 2007 indictment charges Fumo, the high-rolling Philadelphia Democrat, with looting the state Senate, a nonprofit and a museum of more than $2 million in goods and services.

But Fumo — by having virtually all his pre-2005 e-mails destroyed — thwarted the FBI's investigation into millions in donations he sought from Peco Energy and Verizon for the nonprofit, prosecutors said. Peco donated $17 million to the South Philadelphia neighborhood improvement group; Verizon gave nothing.

"The conspiracy ... thwart(ed) the investigators' ability to determine whether federal crimes were committed in connection with those matters," prosecutors said in Luchko's plea memorandum.

Luchko pleaded guilty to all 29 conspiracy and obstruction counts he faced and will testify against Fumo and two remaining co-defendants. In exchange, prosecutors will ask a judge to sentence the 52-year-old to no more than two years in prison.

Through his plea, Luchko admits he was acting on the boss's orders when he destroyed years of e-mails.