Crooked as a barrel of fish hooks or crooked as a dog's hind leg, from TFD
"Don't play cards with him. He's as crooked as a barrel of fish hooks."
"Mary says all politicians are crooked as a dog's hind leg."
Barefaced liar, from TFD
One who tells blatantly obvious and/or impudent untruths easily and with little or no attempt to disguise the lie.
"Everyone knows he is just a barefaced liar. It's a wonder anyone believes a thing he says anymore."
Lie through teeth, from TFD
Fig. to lie boldly.
"I knew she was lying through her teeth, but I didn't want to say so just then."
"If John denies it he's lying through his teeth, because I saw him do it."
"Don't you know she lies through her teeth?"
If the person has been telling lies all their life, try:
Live a lie, from TFD
to live a life that is dishonest because you are pretending to be something that you are not, either to yourself or to other people.
"Walker, who admitted that he was gay last year, spoke of the relief he felt at no longer having to live a lie."
"For all of his adult life, he lived a lie and didn't confess even to his family that he was a spy."