Duffy Haskell first contacted John Doggett (Per Manum) claiming he has had contact with the X-Files office in the past. This time he claimed that his wife Kath McCready who was an abductee, was murdered by her doctors during delivery for her alien baby. He left a sonogram of the fetus with Doggett. Scully was not convinced but hanged on to the sonogram.
When brought in for questioning at Skinner's office, Skinner mentioned that fact that Haskell, being the president of the Ohio Mutual UFO Network, had sent Mulder threatening letters. Doggett told him he cannot find documentation that Haskell was even married and that there was no evidence of foul play on the part of Dr Lev who is a leader in the field of birth defects, whom Haskell accused of killing his wife and stole the alien baby.
In time, it was shown that Haskell actually worked with the doctors at Zeus Genetics, and his contact with the X-Files office was a trap. Meanwhile, Doggett learned that the fingerprints obtained from Haskell belonged to a David Haskell who died in 1970 and was buried in a Virginia cemetery with USMC honour guard ceremony.
He reappeared in Essence, working with Lizzy Gill who was hired to help Scully with her pregnancy.
Duffy Haskell is a character who played by Jay Acovone.