PORTLAND — A 70-year-old Porter man accused of growing more than 3,000 marijuana plants inside his house and on land near his farm has been indicted on federal drug charges.

Leslie E. Roberts has been free on $50,000 unsecured bond since his arrest last August in what drug agents said was one of the largest seizures ever of marijuana plants in Maine.

Roberts was charged with manufacturing and possessing with intent to distribute more than 1,000 marijuana plants. If convicted, he faces a maximum sentence of life imprisonment and fines of up to $4 million, U.S. Attorney Richard S. Cohen said.

Described as a sophisticated grower who used an elaborate pump system to water his plants, Roberts was arrested by Oxford County sheriff’s deputies who had put his property under surveillance when marijuana plants were spotted during a patrol.

In an unrelated case, Cohen said the grand jury handed up an eight-count indictment against a father and son from Dresden, who were accused of cultivating more than 100 marijuana plants.

Guy W. Bolte, 41, also was charged with using and carrying a firearm as part of the marijuana offense. His son, Charles G. Bolte, 18, also was charged with possession of a firearm by a felon.

Also indicted were:

Frank J. Rench, 32, of Portland, charged with mail theft.

Kathy A. Hewey, 35, of Conway, N.H., mail theft and embezzlement from the post office.

Walter E. Fay, 43, of Solon, and Naomi Staples, also known as Tina Staples, of Union, armed robbery of the Damariscotta Bank & Trust Co. in Warren on Jan. 8.

Richard J. Poland, 38, of Portland, robbery of the Congress Square branch of Peoples Heritage Bank last Tuesday.