(Reuters) — Two men pleaded guilty in New Jersey on Thursday to playing roles in a wide-ranging hacking and spamming scheme that targeted the personal information of 60 million people, including Comcast Corp. customers, prosecutors said.

Tomasz Chmielarz, 33, pleaded guilty in federal court in Newark, New Jersey, to charges of conspiracy to commit fraud and related activity related to computers and email, while Devin McArthur, 27, pleaded guilty to conspiracy to commit wire fraud.

Along with a Florida man, Timothy Livingston, 30, they were arrested in December in connection with several alleged computer hacking and illegal spamming schemes that targeted multiple companies and generated illegal profits exceeding $2 million.

Prosecutors said Mr. Livingston, who owned a spam company called A Whole Lot of Nothing L.L.C., hired Mr. Chmielarz, of Rutherford, New Jersey, to write computer programs that send spam in a manner that conceals their origin and bypasses spam filters.

Prosecutors said Mr. Chmielarz admitted that he and Mr. Livingston hacked into email accounts and seized control of corporate mail servers to further their spam campaigns, and created software that exploited vulnerabilities in a several corporate websites.

Messrs. Livingston, Chmielarz and McArthur, a resident of Ellicott City, Maryland, also worked together to steal databases containing the personal information of millions of Americans for use in spam campaigns, prosecutors said.

Prosecutors said Mr. McArthur admitted that he also gave Mr. Livingston unauthorized access to a remote administration tool on a computer connected to the network of a Pennsylvania-based telecommunications company where he worked.

That enabled Messrs. Livingston and Chmielarz to steal the personal information of customers of the company for use in spam campaigns, prosecutors said.

The company was not named in court papers, but Comcast confirmed its identity. Jenni Moyer, a Comcast spokeswoman, said the company appreciates the efforts of U.S. authorities "in bringing this scamming scheme to a just resolution."

Other companies targeted included a New York telecommunications company, a New York technology and consulting company and a Texas credit monitoring firm, the indictment said.

Michael Koribanics, Mr. Chmielarz's lawyer, said his client had "accepted responsibility for his actions as evidenced by his guilty plea." A lawyer for Mr. McArthur did not respond to a request for comment.

Mr. Livingston has pleaded not guilty and is scheduled to face trial on Oct. 13.

The case is U.S. v. Livingston et al., U.S. District Court, District of New Jersey, No. 15-cr-00626.