Brown Eyed Ghoul by H.P. Mallory

The last thing Peyton Clark wants to do is visit the evil voodoo witch, Guarda, again. But once she promises two elderly and kind ladies that she will solve the missing-person case of their long dead relative, she realizes there’s no way around it.
With the help of Guarda’s magic, Peyton will find herself in 1910 New York with none other than Drake Montague, the twentieth century policeman, who used to haunt her house but now haunts her body… and her heart.

While Drake and Peyton begin to unravel the mystery, Peyton can’t help the fact that she’s deeply attracted to Drake, regardless of the fact that her very real boyfriend, Ryan, is back in her own time, eagerly awaiting her return.