Help needed. Burying the Past [Gareth's Parents quest] *spoilers*!

[ignorance[is]bliss]

I am quite stuck here and I beg for your help.

As far as I understood it goes like this:
1) Find Gareth
2) Get inside his house
3) Discover that Jonathan was behind this (either by talking to ghosts or finding his gloves)
-----
9) Find Jonathan
10) During the dialog tell Gareth to kill him or spare him (to get both of those achievements by reload, obviously).

When I finish first three stages I get the quest to kill Magister, but Gareth stays at his house.
I tried different ways. Went all down that place, killed Magister, took his ring as a proff of his death, but this just finishes the quest and Gareth dissapears (no sign of him on Lady Vengeance either).

I guess the problem is that Gareth does to follow me to that Magister camp so I cannot initiate his dialog with Jonathan.

What am I missing, guys? Dialog option? Or did I come here too soon? Maybe doing other 'related' quests might solve this problem? Thanks in advance

[ignorance[is]bliss]

bump :(

[#DWB#Baki]

bump

[Matze]

Hmm... i just killed Jonathan and brought the ring back to his place

[ignorance[is]bliss]

The point was to get achievements for Gareth. But I guess you missed them as I did on my 1st playthrough.

[#DWB#Baki]

try to unlock the door