The system used in Argentina has a paper trail. When a vote is casted the machine saves the voter's choice to an RFID chip inside the ballot and at the same time the same information is printed as human-readable text on the ballot. The voter can use a separate machine to read the RFID and verify that the information printed matches the information stored.
The votes are counted at each polling station primarily using a RFID reader, but each political party can designate monitors to oversee the process. In case of doubts the votes can be re-counted using the printed information. When everyone present agrees on the totals, the results are sent to a central location where they are aggregated. Results from each polling station are made available online so each party can verify that the totals add up correctly.
As a final step, 5% of the polling stations are randomly selected the week after the election and votes are manually re-counted using the paper trail. This is done in the presence of monitors from the different parties. This is the second time this system is used. The first time the audit of the 5% of the polling stations showed no differences.
I think there is a bit of exaggeration on these reports since even if the software is vulnerable, the system as a whole can be verified. The police raids can be explained since some of these "researchers" made available a list of all the employees of the company supplying the voting machines including phone numbers and addresses in an attempt to prove the incompetence of that company