The test involves an instrument that analyzes the constitution of more than a dozen chemical samples, including eight control samples designed to verify the equipment's accuracy. The test is designed to be automated, so that all the steps take place sequentially over a period of about seven hours without any intervention by an operator.
The tests on Landis' Stage 17 samples, however, each appear to have included an unexplained gap of about five hours between two of the steps.
"Tell me what happened here," Suh said to Mongongu, referring to one of the gaps.
She said "there was a problem," and that she had to implement one of the steps manually. Although such a departure from routine normally requires written documentation under WADA rules, Mongongu acknowledged that she made no note of the problem at the time.
Mongongu acknowledged that at several points during the April retests, she intervened manually in the test sequence because the instrument had produced a result that was "undoubtedly not correct." She did not document her action at the time, she acknowledged.
The incorrect or unacceptable results being produced by the machine tended to involve calibrations or verification runs, rather than readings on Landis' samples. But the defense may be intending to argue that the inadequacy of the machine casts doubt on Landis' results.
Mongongu's testimony suggested that the performance of the machine had been erratic for years; under questioning by Howard Jacobs, another lawyer for Landis, she said that she had had to summon a manufacturer's technician roughly 10 times since September 2003 to repair the hardware.
Records of the retesting in April indicated numerous similar gaps in documentation, some of them covering periods of more than an hour. Mongongu testified she could not recall the reason for the gaps.
Mongongu had defended her technique Tuesday under direct questioning by a USADA attorney. On Wednesday, however, she acknowledged that she had failed to document several steps in her analysis of Landis' Stage 17 sample, including where and when she acquired the sample vial and when she passed it on to the next technician in line.