The aim of behavioural identification of Discrete Event Systems is to build, from a sequence of observed inputs/outputs events, an understandable model that exhibits both the direct relations between inputs and outputs events (i.e. the observable behaviour of the system) and the internal state evolutions (i.e. the unobservable behaviour). Since parallelism hinders the construction of monolithic models, distributed identification builds instead models of subsystems. This paper proposes an automated partitioning of the system, optimal regarding the readability of the identified distributed models, thus fitting reverse-engineering purposes. To solve the optimization problem, a first solution is extracted from the observable behaviour, then additional solutions are computed by agglomerative clustering. The approach is applied to a benchmark, resulting in an adequate functional partition.Note to Practitioners-Identification is an approach to obtain models of an existing closed-loop Discrete Event System from an observed I/O sequence, discovering both sequential and concurrent processes within a same system. The result is an understandable and compact model, that approximates the observed behaviour and can be used for reverse-engineering. To get better insight on the behaviour of the system, splitting it into subsystems and studying distributed models might be easier. Besides, identifying smaller subsystems reduces the computational cost. The main contribution of this article is therefore a partitioning approach for distributed DES identification. Only the knowledge of the I/Os and the observed I/O sequence are required to provide a partitioning adapted to reverse-engineering and compact distributed models, in reasonable computation times.