The authors conducted an epidemiological investigation at Cook County Jail, Chicago, Illinois to evaluate the utility of serial testing as a method of identifying asymptomatic and pre-symptomatic cases. Housing units were selected for inclusion if at least one individual tested positive for SARS- CoV-2 and was placed on quarantine. During May 1-19, 2020, two cohort-based SARS-CoV-2 testing strategies were employed: 1) individuals were asked to participate in serial testing (day 1, day 3-5, and day 13-14), and 2) offered a single test and interview to assess current symptoms at the end of the 14- day quarantine. 195 of the 224 individuals approached agreed to participate in at least one component of the investigation. A majority of participants identified as non-Hispanic Black (67%), Hispanic (19%), and non-Hispanic White (6%). Of the 172 tested individuals, 19 tested positive for SARS-CoV-2. In the serial testing group, 17 new cases (89% of confirmed total) were detected: 16 on day 1, one on days 3-5, and none on days 13-14. In the second group, two new cases (11% of confirmed total) were identified. Of the newly identified cases, 63% were asymptomatic. The authors conclude that symptom screening alone is ineffective in identifying new cases and this study supports the utility of early cohort-based testing approaches in detention centers to effectively identify pre-symptomatic and asymptomatic cases.