The secret life on an IRA man living in Pennsylvania has come back to haunt him after his son and daughter were both involved in separate homicides. 

Sean O’Neill, 49, from Coalisland, County Tyrone has been living a quiet life as a builder and bar owner in Philadelphia for the past 25 years but is now facing jail time and deportation back to Ireland.

O’Neill, who is free on $1.2 million bail secured by real estate, is set to plead guilty today (Thursday) in federal court in Philadelphia to five charges including the possessions of weapons, immigration and tax fraud charges. O’Neill will likely face prison time and deportation to Ireland.

It wasn’t until his son, Sean Jr., shot a close friend during a drunken underage gun game that O’Neill’s involvement with Fianna Na h'Eireann, a now-defunct radical youth group associated with the IRA, came out in the open. According to court papers, O’Neill pleaded guilty in Northern Ireland to being a Fianna Na h'Eireann member in 1977.

Sean Jr., now 19, shot his school friend, Scott Sheridan, during Labor Day weekend 2006 while playing with his father’s gun. Police said Sean’s blood-alcohol level was 0.175 at the time, more than twice the adult legal limit.

Sean was found guilty of juvenile manslaughter. He is due to be released this month from his second stint in a juvenile facility.

It was a silencer that police found at the O’Neill’s home after the shooting that provoked an investigation into Sean Sr.  

O'Neill came to the U.S. in January 1983 on a six-month visa. In April, he bought a .38-caliber Colt revolver. O'Neill told the gun dealer that he was born in Irving, Texas, and gave a false date of birth, a story he used to purchase at least three more guns in subsequent years, according to the federal affidavit.

Prosecutors say O'Neill lied about his involvement with an IRA-linked youth group when he came to the U.S. in 1983. They say he married under false pretences just so he could stay here and then married his current wife Eileen without ever getting a divorce from his first wife.

Prosecutors are also charging O’Neill with lying on several gun-purchase applications, paying some employees off the books at Maggie O'Neill's Irish Pub in Drexel Hill from 1997 to 2006, and failing to file personal tax returns from 2005 through 2007.

O’Neill’s daughter, Roisin, 22, is due to stand trial on Monday, April 20, for a homicide that took place last September.

Roisin, the eldest of O’Neill’s children, is charged with killing a Massachusetts grandmother after she drove up the wrong way on a highway while intoxicated.

Police say that Roisin had a 0.197 blood-alcohol level when she left a bar and drove the wrong way on Interstate 476 early last September.

She apparently traveled three miles before striking the car driven by Patricia Waggoner, 63, of Brimfield, Massachusetts. Waggoner was in the area to visit her grandchildren.

 O'Neill Sr. told reporters after the crash that his own legal troubles and potential deportation after a quarter century in the U.S. were "the least of my worries."

"To face every day is just too hard right now," he said as his daughter, arrived for an October court hearing in a wheelchair.