In case you are looking for a maximum of security, you should register your contract with the "civil law notary" with exclusive responsibility in the area of the desired property.

No real estate agent or agency has this authority, nor can give you this much security.

If you do not already have your own assistance we can help you in realising your purchase with a maximum of security or we can indicate professional help (English spoken).

Some extracts regarding civil law notary and notarial act :

"The notary is a state official resident in the area in which you are buying, and is the only person permitted by law to administer the sale of property."

( http://www.guardian.co.uk/money/2004/jul/26/buyingpropertyabroad )

The " notary at civil law " ( civil law notary) is a highly trained public official who drafts private agreements into documentary language and then functions as an archivist of the document he or she creates.
The properly signed contract executed before a notary public at civil law is an "authentic act," deemed to be proof of its contents.
The civil law notarial system is designed to provide a clear and reliable framework for citizens to conduct their legal business.
The notary identifies and guarantees the identities of parties to acts, witnesses the agreement, reads the act aloud to the parties, and affixes his official, distinctive signature to it.

http://www.notarialarchives.org/civil.htm

A " civil law notarial act " is a structured private sector contract that is preserved in the public sector.
The properly executed notarial act bears upon its face the evidence that all the formalities required by law for validity have been complied with.
It contains a statement of the notary's authority, the date, the place of execution, and the identities of parties to the agreement.

( http://www.notarialarchives.org/civil.htm )

It states the object of the agreement, its terms, an acceptance, and the consideration.
The notary's original signature at the end of the act provides prima facie evidence at civil law that the agreement he witnessed actually took place and is therefore enforceable between the parties, by society if need be.
( http://www.notarialarchives.org/civil.htm )

The most common areas of practice for civil law notaries are in property conveyancing and registration, contract drafting, commercial transactions, successions and other estate related matters. In some jurisdictions such as France (/wiki/France) or Italy (/wiki/Italy), they also maintain the official registration of property records.
This is also the case in Brazil in the exclusive notary in charge ("cartório único") in the civil law notarial district of the property ("comarca") ( the municipal of Touros in our case )