Alfa 159 2.4 jtdm - oil leak

[Marc000000]

Hi,

My alfa 159 2.4 diesel was working well, but this morning I noticed an oil spill under the engine on the drivers side.
I have cleaned all the oil with degreaser as best as possible, but it is still not easy to locate the source. Areas that are definitely not leaking is the filter and sump drain cap.
I'm thinking it may be the crank shaft seal. Is this relatively easy to replace?
What other things could be leaking on the drivers side of the engine?
Your comments would be appreciated.
Regards
Marc