He met the girl through an internet chat room after filling in an online profile in which he described himself as 19.
The relationship with the girl, from Clackmannanshire, was conducted using a live weblink.
Ross, 31 and formerly from Dundee but now of Dennistoun in Glasgow, was also put on the sex offenders' register.
It is alleged that he then hid the body under the floor of the church in an attempt to defeat the ends of justice.
In a "special defence" read to the jury Tobin admits having sex with the Polish student with her consent.
Tobin, who was known to the priest as Pat Mc Laughlin, was building a shed and Miss Kluk was helping him to paint it.
He added: "About 2.30pm that afternoon I popped into the garage and saw Pat and Angela there.
Detective Sergeant David Nolan, who works for the computer crime unit with Central Scotland Police, said: "The internet's a wonderful place where children can go onto live webcams across the world, they can speak to friends and relatives on live webcams, but it does have its darker side where paedophiles can groom children.