Fabio Ongaro got Italy's first try of the campaign and his first for his country - which should not have been given as he knocked it on - while Simon Webster grabbed a late consolation effort for the Scots as they went down to a defeat they probably fully deserved.
The victory probably ensures that the Italians Kiwi coach John Kirwan gets a new contract at the end of the season after several papers had suggested this was his do or die match - he even received a bullet from a so-called fan in the post.
Ongaro will seldom score a more fortuitous try in his career as the hooker pounced in the 42nd minute after Stuart Grimes had batted the ball back from an Italian line-out three metres out from the Scots line.
The Italian hooker shoved his opposite number Gordon Bulloch out of the way and appeared to knock the ball on over the line before grounding it - the try was awarded by referee Nigel Whitehouse but if he had referred it to the video judge the 26-year-old Ongaro might well have not broken his duck in tests. However Ongaro's try - his first in 19 tests - seemed to spark some self-belief into the Italians and Scotland were fortunate to clear their lines a few minutes later after Paul Griffen's shrewd grubber kick had them in all sorts of trouble.
The Italians had to reshuffle their backline in the 46th minute when Manuel Dallan was unluckily injured after Jason White tackled ,b>Sergio Parisse, inadvertently knocking the centre to the ground in the process and he was replaced by the Kiwi-born Rima Wakarua, whose mother is Scottish.
Paterson missed an opportunity to reduce the deficit to just two points on the hour mark but his penalty went wide of the posts to the right. The Scots, though, produced their most flowing piece of play in the match seconds later whenb winger Simon Webster's darting run saw him beat three players but he stumbled just short of the line and the Italians won the ball back after the visitors failed to take advantage even though they encamped on their line.
De Marigny's faultless display with the boot - the conversion attempt apart - handed the hosts a crucial penalty 10 minutes from time - after a storming run from ,b>Cristian Stoica forced the Scots into an infringement - which edged them more than a converted try ahead of their ragged opponents at 17-9.
De Marigny, son of French aristocratic stock who moved to Mauritius, ensured that Italy wrapped up the match with another sweetly struck penalty three minutes from time leaving Kirwan hammering the desk in relief and satisfaction.
Webster's late try was little more than consolation for the woeful visitors but just reward for his efforts for being the Scots most incisive back.
De Marigny had given the Italians an early lead with a crisply struck penalty from wide out on the left but the Scots drew level in the ninth minute as Paterson slotted a penalty over after an infringement by the hosts scrum.
Two minutes later de Marigny restored the three point advantage with another penalty - this time in front of the posts - after Simon Taylor came in at the side of the ruck.
The Scots did draw level eight minutes from the break when Paterson converted a penalty right in front of the posts after one of the few genuine penetrating phases of handling the ball started by Kiwi-born centre Brendan Laney.
Paterson then gave Scotland a barely deserved lead in the 39th minute capitalising on another Italian infringement to kick a penalty and give them a 9-6 lead. However de Marigny's unerring boot handed the hosts another three points to send the two sides in on level terms after a distinctly underwhelming first 40 minutes.
AFP - 2004.
