Edward F. Bachner IV, 35, also was charged with lying to the IRS in an effort to collect more than $538,000 in income tax refunds for three years the government didn't owe him.
The bizarre case surfaced in July when federal agents arrested Bachner after catching him taking delivery of a shipment of tetrodotoxin, which can be fatal when fish containing the substance are eaten. It is 1,200 times deadlier than cyanide, according to the U.S. Food and Drug Administration.
Agents also found syringes, needles and a book on how to poison people when they searched his home in suburban Lake in the Hills, prosecutors said.
A message seeking comment was left Tuesday for defense attorney James Marcus, who has said the book was a reference work for would-be crime novelists. Marcus also has questioned whether a plot to kill Bachner's wife existed. Rebecca Bachner has attended her husband's court proceedings since his arrest.
Bachner originally was charged with lying to get the toxin, claiming it was for scientific research. The FBI said in an affidavit that a cooperating witness received several anonymous messages in 2005 soliciting the killing of an unnamed woman in the Chicago area. One of the messages offered payment of $8,000 and an AK-47 assault rifle for the job.
Tuesday's indictment charged that Bachner bought the toxin for the specific purpose of killing his wife and collecting life insurance. Bachner made a wire transfer of $39,989.49 from his bank account to Peterson International Underwriters of Valencia, Calif., in February 2008 to buy the $20 million policy, according to the indictment.
Bachner has been in federal custody since his arrest and U.S. District Judge Federick Kapala in Rockford has denied several bond requests, saying he wasn't convinced Bachner was no danger.