As Realtors, we can not discuss crime areas, crime rate for a specific area. The best place to ask will be the local policy station.
Here is a link to check on neighborhood statistics (including Crime statistics) for East Petaluma (94954) and West Petaluma (94952).
Petaluma has some very distinct areas, each with unique charectistics; all depend on the type of neighborhood, style of houess, amendities, etc you are lookiing for.
Please let me know if I can help you further.
The City of Petaluma has a website which discusses crime prevention in Petaluma neighborhoods. They say they will be adding a graphical display of neighborhood statistics. http://cityofpetaluma.net/police/crimeprevention.html
You can also try googling Petaluma Crime statistics to see what you come up with and contact the Sonoma County Sheriff's Department as well. As Realtors we are not allowed to provide this information to you. Be aware that some areas in Sonoma County fall under the county's jurisdiction if the homes are outside a particular city limits. Since so many residences here are rural that is often the case. Good luck with your search.