Ralf,
The 10m croc reported by Wermuth and Fuchs has since been disproved. The skull is held by the BMNH, if I remember correctly, and comes out at 17 or 18 feet by extrapolation (that's around 5 metres, not 10 m). The 8.5 metre croc from Queensland has also never been proven, and frankly I have great trouble believing the apparent comedy of errors that the experienced and bush-savvy hunters must have made to prevent any evidence from surviving.
The largest crocodile that can be proven - ie. was measured with a tape measure by a zoologist - was a recently skun croc from Papua New Guinea. This skin measured just over 6.2 metres (20.3 feet), was missing approximately 10cm of its tail, and being a skin would have been a slight underestimate of total size.
There is a skull from Orissa, India, that when extrapolated up would have come from a 21 to 23 foot long crocodile, but without the whole animal its real size is a mystery.
There are plenty of photos and stories, but as far as I'm concerned I like to see someone use a tape measure! Having seen a lot of wild C. porosus, a lot of measurements of wild C. porosus, and the size range they typically grow to, I can believe a croc in the 20 to 23 foot range would be rare but possible. But 27 - 28 feet (8.5 metres)...? Exaggeration seems a far more likely explanation in the face of insufficient evidence.