adjective, guilt·i·er, guilt·i·est.
Examples from the Web for guiltier
Yes, you—don't shrink—you drove him to it; and you would have been the guiltier of the two.
If he'd been caught in the act of borin' into the bond safe he couldn't have looked any guiltier.Torchy As A Pa|Sewell Ford
I may make myself worse an' guiltier; but unhappier I cannot be.The Black Prophet: A Tale Of Irish Famine|William Carleton
And all the time Jerry felt guiltier and guiltier and the half-dollar in his pocket seemed to become bigger and heavier.The Circus Comes to Town|Lebbeus Mitchell
I don't think her father is guiltier than a great many other people who haven't been found out.The Quality of Mercy|W. D. Howells
British Dictionary definitions for guiltier
adjective guiltier or guiltiest
Word Origin and History for guiltier
Old English gyltig, from gylt (see guilt (n.)). Of conscience, feelings, etc., 1590s. Meaning "person who is guilty" is from 1540s. To plead not guilty is from 15c.; to plead guilty is 19c., though, as OED notes, "Guilty is technically not a plea, but a confession."