As-Salamu'Alaykum sister.I can imagine a situation where i might use a service such as you decribed.In an ideal world we would all have good Muslim fathers and brothers to do the research for us,but those of us who are divorcees or reverts often don't.If the prospective partner is a good person they will understand the reasons for it.
(In the UK they've just brought in a law so that single mums can check out new boyfriends with the police to ensure their kids safety.Why shouldn't we want the same peace of mind?)

B .

ok.. im telling real story of my sister, her hubby came to Indonesia, so he and my sist can see each other face to face, and after 2 weeks, they married.. the end.

im not sure about investigations things are good or bad.. but dont u think this is to much..i mean.. its about between 2 party and between them theres wali.. and wali should more responsible for this stuff.

anyways, good luck sist. and my advice is just do not closed enough to see details of the person.. just the basics things like what is he doing.. hows the family background, and see she/he friends too.

Assalam akaylum
Check for privacy laws, in some countries or states, they will not give out some information without the person's consent.
You could go around the community to see if he has a very good reputation and also see if the person has the motivation and the proposal to start such a business venture.

On a personal relationship. I would gather the information around the person like visiting the masjids or family members or friends

there are many corporations which dose background check which cover (immigration, credit history... blah blah blah) if you are considering a business of background check specially for marriage issue of muslim ummah then you need to put some clauses which are not being affored by existing corporations.

1. Coordinate with the local imam of masjid's where brother stays to check how often he visit masjid

wasalam.

Don't forget the blood test, drug test, credit check, immigration policy violation, trouble with local community, DNA test. If possible, find out the IQ number also. And you must not miss CarFax history report. Hire a private investigator to follow your spouse around for couple of years.