Franco Cerrina, a Boston University engineering professor, was found dead in a lab at BU’s Photonics Center on Monday morning, the university reported yesterday. He was 62. Colin Riley, a BU spokesman, said in an e-mail this morning that the cause of death is not yet known. Police are not treating Cerrina’s death as a criminal matter, according to BU. Cerrina joined the faculty of BU in 2008 after spending 24 years on the faculty at the University of Wisconsin-Madison. He co-founded five companies, including NimbleGen Systems, Genetic Assemblies (merged with Codon Devices in 2006), Codon Devices, Biolitho, and Gen9, according to Nanowerk News. NimbleGen, a Madison, WI-based provider of DNA microarray technology, was sold to Basel, Switzerland-based Roche in 2007 for $272.5 million.