The accused Mohammad Javed, (45), contractor of the adjacent building, was arrested after a case of causing death by negligence was lodged against him yesterday.
Locals said four-storey building number 313/4C, built on a plinth area of 25 square yards, fell down like a pack of cards around 8:40 AM.
Construction work at the adjacent plot of about 20-22 sq yards, is being suspected as one of the reasons behind the building collapse.
"The work on the plot had started two months ago. A 15-foot-deep digging on the plot weakened the foundation of the four-storey building which apparently led to its collapse," Deputy Commissioner of Police (North) Madhur Verma, said.
The plot was owned by Javed's sister, police said.
Ten people including three women and five children were killed and two others injured when the 50-year-old dilapidated four-storeyed building collapsed in a congested area in north Delhi.