spiral. As a result, optical emission lines will be dominated by the emission from star formation regions, severely limiting the diagnostic power of optical surveys in determining the incidence of accreting black holes in low-bulge systems. In our previous work, we demonstrated the power of mid-IR spectroscopy in detecting the low-power AGN in the Sd galaxy NGC 3621 (Satyapal et al. 2007; henceforth S07). AGN show prominent high ionization fine structure line emission at mid-infrared wavelengths but starburst and normal galaxies are characterized by a lower ionization spectra characteristic of HII regions ionized by young stars (e.g. Genzel et al. 1998; Sturm et al. 2002; Satyapal et al. 2004). In particular, the \[NeV\] 14 $\mu$m (ionization potential 97 eV) line is not generally produced in HII regions surrounding young stars, the dominant energy source in starburst galaxies, since even hot massive stars emit very few photons with energy sufficient for the production of Ne4+. The detection of this line in any galaxy provides strong evidence for an AGN.

The goal of this paper is to answer the question: are AGN in late-type galaxies more common than previously thought? If so, this would revise our understanding of the environments in which 