Did you just find a file that has a digital signature from Marek Jasinski? If that's the case, please read on.
You will typically notice Marek Jasinski when running the file. The publisher name is then displayed as the "Verified publisher" in the UAC dialog as the screencap shows:

You can view the digital signature details for Marek Jasinski with the following steps:
Here's a screengrab of a file digitally signed by Marek Jasinski:

As you can see in the screenshot above, Windows reports that "This digital signature is OK". This implies that the file has been published by Marek Jasinski and that no one has tampered with the file.
If you click the View Certificate button shown in the screenshot above, you can examine all the details of the certificate, such as when it was issued, who issued the certificate, how long it is valid, etc. You can also see the address for Marek Jasinski, such as the street name, city and country.
COMODO Code Signing CA 2 has issued the Marek Jasinski certificates. You can also examine the details of the issuer by clicking the View Certificate button shown in the screenshot above.
The following are the Marek Jasinski files I have gathered, thanks to the FreeFixer users.
| Detection Ratio | File Name |
|---|---|
| 0/61 | FcContextMenu64.exe |
The detection percentage is based on that I've collected 61 scan results for the Marek Jasinski files. 0 of these scan reports came up with some sort of detection. If you like, you can view the full details of the scan results by examining the files listed above.
The analysis has been done on certificates with the following serial numbers: